Pressure Spike in Smokeless Powders

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Pressure Spike in Smokeless Powders

Post by Pop Watts »

Has this been covered before? Please excuse me if it has.

On the weekend just gone I got into a conversation with an experienced Single Action shooter who was horrified to learn I use smokeless powder in some old Black powder guns ( Colt Baby Lightning, 1873 Winchesters and early 1892 Win, all in 44-40 )

He assures me I will get a pressure spike with every shot and this will damage these old girls.

My loading data from ADI ( Australian powders ) show maximum pressures of 10,000 to 12,900 PSI depending on load. That is max loading and I never go that high, so pressure will be under these figures. The loads are listed for single action hand guns.

How would these pressures compare to original black loads and is this pressure spike a reality?

What's the science behind it?

Anyone know?

Thanks, Pop.
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Re: Pressure Spike in Smokeless Powders

Post by Tycer »

KirkD should be along to help out. I believe he uses some smokeless in his old girls.
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Re: Pressure Spike in Smokeless Powders

Post by Pisgah »

There's a pressure spike with every powder, black powder included. In fact, BP pressure "spikes", or hits maximum for the load, faster than most smokeless powders.

What your friend may be thinking of is a somewhat controversial phenomenon called "detonation". Supposedly, some very fast powders loaded in small charges in large cases can burn with excessive pressure and destroy a gun. The idea is controversial because although many swear it has happened, and there are many theories as to how and why, the phenomenon has never been successfully reproduced under laboratory conditions. What HAS been shown to reproduce the identical results is a double charge of those same powders -- in other words, since the case volume is so large and the powder volume so small a reloader can easily, unintentionally, double the charge and blow up the gun.

Black or smokeless, the rule remains the same -- use reliable, tested data and MAKE SURE every case contains a proper powder charge.
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Re: Pressure Spike in Smokeless Powders

Post by KirkD »

This has been discussed in detail in the past. A search might find it. In general, smokeless powders like Blue Dot and 2400 give approximately the same pressure curve as black powder FOR THE SAME VELOCITY AS BLACK POWDER AND THE SAME BULLET AND BULLET WEIGHT. Smokeless powders with a faster burn rate like Unique, Trail Boss, Bullseye, etc. will give a higher, sharper pressure spike. Slower smokeless powders like IMR 4227, IMR 3031, RL-7, etc. will give a lower, rounder pressure spike. Sherman Bell had some good articles on this a few years ago in the Double Gun Journal. Others have posted pressure curve comparisons. Some examples are below:

Image

Image

In the above data, he used a 410 grain bullet with IMR SR4759. To compare apples to apples, you should increase the peak pressure by 25% to compare with the 500 grain bullet. This will raise the peak pressures to be pretty much identical with FFg and still lower than FFFg, but higher than Fg. It will also reduce the 'rise' (the length of the curve).

Sherman Bell, in his comparisons (not shown here) used the same bullet but with different smokeless powders and black powder. What he showed is that slower smokeless powders (he used IMR 4198, IMR 3031 and RL-7) can give the same or higher velocity with lower pressure, including lower peak pressure (for the same case, same bullet and same velocity). Thus, the right kind of smokeless powder is actually easier on your old guns. You might think, therefore, that the slower the powder the better. Not so. If the pressure gets too low, it fails to expand the case to seal against the chamber walls, and two things happen. First, the outside of your cases get all sooty. Second, and worse, all the axial thrust is against your bolt face, which you don't want for toggle link actions like the Winchester Model 1873 and 1876. Thus, I use only a narrow range of smokeless powders in the 1873 and 1876 that runs in burn rate between 2400 and 5744, with 5744 being at the slower end of the range.

So my procedure is to first find a load using a powder in that burn rate range that will give me original black powder velocities. If the case is sooty, I keep the velocity the same, but go to a slightly faster powder, until the case eject clean. Then I know I have sufficient peak pressure to temporarily bond the cartridge case to the chamber walls during firing. For original old guns, I stay away from fast powders. For the same black powder velocity, they give way too high peak pressures. Take a look at the Trail Boss pressure curve above, for example. If you like to use Trail Boss or Unique or other real fast powders, you need to back down on your velocity accordingly, or back down on your bullet weight.

For some information on burn rates and relative quickness of different powders, check out http://www.chuckhawks.com/powder_burning_speed.htm and use IMR SR4759 as being equal to FFg for comparison purposes. Blue Dot is approximately equal to FFFg and 2400 a little closer to Fg. You should also know, from Sherman Bell's work, that IMR 3031 has an erratic burn rate. I find that 2400 has an even more erratic burn rate (gives high extreme spreads in velocity under certain conditions). I like to have quite a bit of air space when using 2400 to reduce extreme spread, and with IMR 3031 I use a filler to reduce air space, which reduces extreme spread.

In general, if you are going to use smokeless powders in old black powder guns, you need to stick with published loads that give velocities similar to black powder velocities. Do not hot rod your old black powder guns. Developing smokeless loads for black powder guns is for more advanced loaders who understand what the burn rates and relative quickness of various powders mean as far as pressures.
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Re: Pressure Spike in Smokeless Powders

Post by bdhold »

old news or not - thanks, Kirk - excellent presentation of the answer...
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Re: Pressure Spike in Smokeless Powders

Post by J Miller »

Kirk,

What do you think of IMR SR4756 for b.p. duplication loads?

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Re: Pressure Spike in Smokeless Powders

Post by Hobie »

Thanks Kirk. This was a regular topic of discussion on the CAS board as there was a rather vehement element opposed to the use of any other than the sacred BP.
Sincerely,

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Re: Pressure Spike in Smokeless Powders

Post by KirkD »

I have a soft spot for BP myself. Shooting is more enjoyable with BP in my opinion.

Joe, I've not used IMR 4756, but looking at the burn rate chart, it looks a little too fast for my tastes. For the same velocity and bullet weight, it would give a pressure spike that is higher than FFFg. I don't know exactly what the comparison would be between FFFg and 4756, however. I sure wish there were a lot more pressure curves published for various cartridges. You'd think that in the 21st century, we would have moved beyond simple load tables and have an abundance of pressure curves for a plethora of cartridges, but it still seems to be not the case. We need a 21st century version of Ken Waters who would spend the next 10 years getting this kind of info for a full range of black powder cartridges. I'd like to see both BP and smokeless pressure curves for all the well known black powder cartridges.
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Re: Pressure Spike in Smokeless Powders

Post by Old Time Hunter »

Kirk, and my apologies to Pop, I have a question regarding a specific smokeless load for my Trapdoors. I use 29.5 grains (=/- .3) of H4198 behind a 405 gr LFN that yields an approximate range of 1275 fps to 1380 fps depending whether or not out of one of my carbines or one of my rifles. I have come to the 29.5 grain load based on the amount of unburned kernels of powder when I started at 27 grains and slowly worked up to the 29.5 grains where I occasionally have a one or two unburnt kernels in the breach when I extract the spent cartridge and very, very rarely have any blowback from an unexpanded cartridge. My question is, am I pushing the pressure limits of the original Trapdoors? They have a hell of a kick, especially in the carbines compared to the BP loads. I am especially worried about my '73 hi-arched breech block rifle as it has a sub-2k serial number that still retains the original firing pin spring (all subsequent serial numbers do not have firing pin springs). I still load my BP substitute stuff (Pyrodex) with 62 grains, .030 veggie, behind a 20-1 cast hollow based 420 grain sized .461" bullet that yields anywhere from 1340 fps to 1440+fps depending on whether a carbine or rifle. When I load that same bullet infront of 70 grains Goex FFg the velocity drops to 1180fps to 1290fps depending. Because I also use the smokeless load out of my 1886, I want to stick with it. Also two of my Trapdoors have Hoyt liners in them that require a .459" or less pill(which the '86 uses also and my '85). The smokless has enough oomph to bump up in the standard Trapdoors (.460" major dia), but if I use BP or Pyrodex the .459's keyhole on the stock bore Trapdoors. Is there any pressure spike information or formulas to illustrate the pressure spikes between my loads?
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Re: Pressure Spike in Smokeless Powders

Post by KirkD »

Old Time Hunter, there are a couple things I can say. My Hornady book lists H4198 as right next to, and very slightly slower than IMR 4198. I will treat them as the same here, though at maximum pressures that might not be wise.

First, Ken Waters lists 33 grains of IMR 4198 under a 414 grain cast bullet as safe for an original Trapdoor, so your 29.5 is likely quite safe.

Second, I'm using 30 grains of IMR 3031 and 1/4 tsp of COW filler under a 500 grain bullet in my original Trapdoor with excellent results. But IMR 3031 is significantly slower than IMR 4198.

Third, I checked Sherman Bell's article, since he compared IMR 4198 with FFg in one of his articles. In general, he has found that IMR 4198 works well as a general rule if it is used at 40% of the FFg load. For example, if an original 45-70 load was 70 grains, 28 grains of IMR 4198 would give very close to the same results. He provides one example using an original Alex Henry double rifle (A 458 caliber that originally used 120 grains of FFg under a 370 grain jacketed bullet). A load of 120 grains of FFg produced a velocity of 1,812 fps and a breech pressure of 21,600 psi. 48 grains of IMR 4198 gave a higher velocity of 1,952 fps, but at a nearly identical breech pressure of 21,700. He also found that if he reduced the charge of IMR 4198 to match the original FFg velocity, he got a breech pressure of only 18,900 psi (2,700 psi lower than FFg). I should add that he used a cork wad overtop his IMR 4198, so that would up pressure slightly. I prefer COW.

Your load is giving you almost 100 fps more velocity than FFg, and you are over the 40% recommended load by Sherman Bell. I would gather from this that your H4198 load is giving you a bit more pressure than FFg. Whether it is safe or not is another question. Ken Waters says that it is. I can see why your load would bump up better than FFg, since it has a bit more pressure, but I don't see why Pyrodex is not doing the job. I have not seen a pressure curve for Pyrodex but I do know that a lot of times it will give faster velocities than even FFFg. I wonder if it has a lower, but longer curve? That would explain why it does not bump up (if bumping up is actually the real problem).
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Re: Pressure Spike in Smokeless Powders

Post by Old Time Hunter »

Thanks for responding Kirk, you offered some relief from my concerns as I have not had any information pertaining to either Ken Waters or Sherman Bell's studies. I will have to look it up. My 'oldest' Trapdoor, being the weakest breech blocked model concerns me the most as I have been told that the high-arch was the weak point of the action. Not having specific data from an acknowledged sorce, I was told via internet that the high-arch should be kept under 18k psi compared to the low-arch and 1884 design of 24k psi.

In regards to using Pyrodex RS, I will contact Hodgdon's and try to find out whether or not they have a pressure curve chart for cartridges. I know it is almost blasphemy to some folks, but the stuff is growing on me and I have two 8lb cases that were given to me free.

Pertaining to the bumping up issue, it might be because of my hard (BHN of 17) cast lead bullets that are sized .4585" compared to my 20-1 (BHN of 11) hollow points that are sized .461". The .4585's work fine even with BP or Pyrodex in my two lined Trapdoors, along with my 1886 and 1885 hi-wall, but, they do not work at all with BP or Pyrodex in my other four all original Trapdoors. The four all originals slug at .460-.4605", standard groove depth for the .45-70 Government back in the day for military. If I shoot 3 -4 rounds and let some fouling build up, they will shoot the .4585's ok and stop keyholing, but never the 1-2" MOA I get with the larger, softer, Hollow Base bullets.

Thanks for the reply though, and again, I have to apologize to Pop for stealing his thread.
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Re: Pressure Spike in Smokeless Powders

Post by Griff »

Hobie wrote:Thanks Kirk. This was a regular topic of discussion on the CAS board as there was a rather vehement element opposed to the use of any other than the sacred BP.
Ditto Kirk. Hobie, I just don't understand WHERE some of them folks get their ideas. Sure, BP is fun... but, we should all acknowledge that it ain't for EVERYONE. Some folks just love to use their stinky chemicals in order to feel their popguns are "clean!" :twisted:
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Re: Pressure Spike in Smokeless Powders

Post by Sixgun »

Don't know about all the scientific stuff that Kirk knows. (Man, that was informative Kirk--thanks :D )

I do know (like others have said) that keeping the smokeless velocities comparable with black velocities is the way to go. I've been shooting Colt Lightnings, 1873 Winchesters, Sharps rifles, old Colt & S&W revolvers, etc for close to 40 years. Several hundred thousand rounds later, I'm fine and so are the guns. (well, one exception and I won't get into that)

I never did like 2400 for the pistol calibered leverguns or revolvers with reduced loads that equal BP ballistics. Burns dirty with wide velocity variations. I like Unique. :D 7 grains of that in a 44-40/38-40 case with the standard 200/180 grain bullet is fine. One Colt Lightning I have has eaten up over 4,000 of those and is still nice and tight. I could list another hundred guns but you get the picture-------use common sense--------------Sixgun
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Re: Pressure Spike in Smokeless Powders

Post by Hobie »

Griff wrote:
Hobie wrote:Thanks Kirk. This was a regular topic of discussion on the CAS board as there was a rather vehement element opposed to the use of any other than the sacred BP.
Ditto Kirk. Hobie, I just don't understand WHERE some of them folks get their ideas. Sure, BP is fun... but, we should all acknowledge that it ain't for EVERYONE. Some folks just love to use their stinky chemicals in order to feel their popguns are "clean!" :twisted:
For me the concern is that BP might just be banned because it is explosive. One would then be forced to use smokeless powders. An ability to adapt and knowledge to do so is important to me.
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Re: Pressure Spike in Smokeless Powders

Post by KirkD »

It would be a very sad day if or when people no longer used, or could use BP.

I should say that the IMR 4198 40% rule might not work for pistol size cartridges. I found that 19.1 grains of IMR 4198 in my 45 Schofield under a 250 grain bullet gave 773 fps. The original BP charge was 28 grains for somewhere around 840 fps. So the 40% rule did not work for that small cartridge. It may only work for the larger capacity rifle cartridges.
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Re: Pressure Spike in Smokeless Powders

Post by AJMD429 »

THANKS KIRK, for the awesome information....! 8)

I'd never seen it explained in such detail.
J Miller wrote:What do you think of IMR SR4756 for b.p. duplication loads?
I thought IMR SR 4759 was closer to b.p. - it's what is recommended in my Savage muzzleloader...???
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Re: Pressure Spike in Smokeless Powders

Post by KirkD »

Sixgun wrote:I never did like 2400 for the pistol calibered leverguns or revolvers with reduced loads that equal BP ballistics. Burns dirty with wide velocity variations.
I agree. I always get large extreme spreads with 2400. It is a useful powder, but I sure don't like it.
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Re: Pressure Spike in Smokeless Powders

Post by J Miller »

Kirk,

SR4756 is too fast, 2400 is inconsistent and dirty at low pressures. So what would you try to duplicate the velocity and black powder pressure in the .45 Colt?

I may have asked this before, if so please forgive.

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Re: Pressure Spike in Smokeless Powders

Post by KirkD »

Currently, I am using IMR 4227 for my 45 Schofield loads, loaded to 45 Colt ballistics. However, I am getting some soot on the outside of my cases, an indication that the peak pressure is a bit low. I might suggest trying IMR SR4759. I'm using that powder in my 38-40 with good results and clean cases. You might also get away with 5744. I found that worked well in my 44 Russian. I have not tried Blue Dot, but that might work better than 2400. It is faster, but roughly equivalent to FFFg in its burning curve. I did reload for the 45 Colt years ago, but in a rifle and didn't try to reproduce BP loads, so I don't have any experience with this cartridge in duplicating BP loads.
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Re: Pressure Spike in Smokeless Powders

Post by Griff »

I use 5744-XMR when I want to duplicate a BP cartridge load. I simply emailed Accurate Powder for recommended load data for my cartridge/gun/bullet combinations and a few days later I got good, solid recommendations from their ballistician. I gave them specific load data for the BP loads I had been using. They were uncannily precise.

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Re: Pressure Spike in Smokeless Powders

Post by J Miller »

I'm envious of those who can use that 5744 successfully. I did try it and found it to be the filthiest, most incomplete burning powder I've ever used. There were days when I'd shoot a cylinder full, point the muzzle up and rotate the cylinder while the cases fell out. After a box full I'd have enough UNburned powder in a pile to load another round. Plus that which was in the gun.
When shooting it from my lever guns I would get sprinkled by unburned kernels as the empty case ejected. I have one box of ammo loaded with that stuff and when it's shot up I will NEVER buy another can of 5744.

I just might try the SR4759. But with the projects I have in line it will be a while.

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Re: Pressure Spike in Smokeless Powders

Post by w30wcf »

To add a little additional information to the excellent info that Kirk has posted (thank you Kirk), early .45-70 smokeless cartridges were loaded with 28 grs. of DuPont Bulk Smokeless No 1. DuPont No1 was known as "low pressure smokeless" back then. 4198 has an almost identical burning rate to No 1 smokeless. The same charge of both powders produce similar velocities.

The Lyman Cast bullet Handbook shows a charge of FFG and 4198 giving similar velocities and the pressure with 4198 is lower than b.p. The exact data is on Hobies pages.

DuPont No. 2 bulk smokeless was used in cartridges like the .38-40 and .44-40. It's burning rate is very similar to 4227.

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Re: Pressure Spike in Smokeless Powders

Post by Pop Watts »

Thanks for the replies and a special thanks to Kirk D for the great information.

Armed with my knew knowledge I checked all the loads I have been using and I am well and truely on the safe side.

Checking burning rates of Australian made ADI powders the equivelant of IMR4227 is AR2205 and IMR4198 coresponds to AR2207. Other powders in the range that will give low pressure spikes with equivelant bullet weights and velocities to black powder loads are BM1, BM2 and AR2207.

Thanks again, learned a lot.

Pop.
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Re: Pressure Spike in Smokeless Powders

Post by w30wcf »

A bit more info.....

I am a student of black and smokeless powders (obsolete and current) and have a number of resources at hand…..some dating back to before 1900. The information being presented has been taken from reputable sources….Winchester catalogs, early smokeless powder pamphlets, etc.

Winchester began their development of smokeless ammunition for b.p. cartridges in the late 1893-1894 time period. They started introducing these types of smokeless cartridges in late 1894 and development continued over the next few years .
U.M.C. was about 1 year behind Winchester in their testing.

THere is nothing printed on the early smokeless ammunition boxes to indicate that they should not be used in b.p. rifles. As a matter of fact, here's a pic of an early smokeless box and it indicates that the cartridges were to be used in the 1873 Winchester. I have yet to hear of a ’73 rifle that failed using factory smokeless ammunition.
Image

The powders that Winchester and U.M.C. initially used were DuPont No. 1 and DuPont No. 2 bulk smokeless powders. No 1 was intended for larger cartridges like the .45-70 and had a burning rate very similar to 4198. No 2 was used for the smaller cartridges like the .38-40 & .44-40. It had a burning rate similar to 4227. The bulk smokeless powders did fill the capacity of the cases, thus the term "Bulk, whereas the "dense" type powders do not.

Shortly after 1900, the factories switched to “Sharpshooter”, a "dense" type powder which was initially produced by Laflin & Rand, then DuPont and finally Hercules. It's burning rate is a tick faster than 2400, actually falling between Blue Dot & 2400.

Note: Alliant has published smokeless data for the .44-40 with no disclaimer that it shouldn’t be used in a ’73 Winchester rifle.

I have a ’73 Winchester that was made in 1882. I shoot both smokeless and b.p. ammunition in it. To date, it’s hammer has dropped on about 2,500 hand loaded smokeless and 1,000 b.p. cartridges. Smokeless cartridges were loaded with slower burning 4227 which were pressure tested at a ballistics lab and produced pressures within the SAMMI MAP (max average pressure) specifications for the .44-40. It’s still working great.

Back to the 1800's......In the .45-70, the charge weight of DuPont No 1 bulk smokeless was 28 grs. and was indicated to produce velocities and pressures similar to 70 grs. of black. As has been mentioned, DuPont No. 1 was similar in burning rate to 4198. Thus, the 40% rule was born (28 / 70). In other words, as a rule of thumb, with 4198, use a charge that is 40 % of the charge weight of b.p.

Let’s see how that works out.
The Lyman ballistic laboratory recorded the following .45-70 loads for velocity and pressure. The similarity is remarkable!
From the Lyman Cast Bullet Handbook:
Bullet weight: 420 grs.
70.0 grs./ FFG / 1,268 f.p.s. / 16,400 C.U.P.
28.5 grs./ 4198 / 1,267 f.p.s. / 13,900 C.U.P.
Interesting that less pressure was produced with the smokeless load.

The history of smokeless powders used by the factories in black powder cartridges is a very interesting subject.......and fraught with a lot of misconceptions.......

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Re: Pressure Spike in Smokeless Powders

Post by Pop Watts »

OK, so I am still learning a lot here.

w30wcf, can I ask you what you believe to be amount of 4227 required to reproduce Black Powder ballistics in the 44-40 with 200 and 240gn projectiles? And, was there any velocity increase in the smokeless powder loads made for 1873 rifles over the BP loads?

Thanks, Pop.
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Re: Pressure Spike in Smokeless Powders

Post by KirkD »

Joe: I have found 5744 to leave a generous amount of unburnt powder unless capacity or near capacity loads are used, or unless filler is used. My capacity load of 5744 in the 44 Russian left little if any unburnt powder. Same with my filler loads. However, for my 45-60 I use 5744 in spite of the unburnt powder simply because 5744 is less position sensitive than, say, IMR 4227. Actual chronograph data showed a 200 fps difference with IMR 4227 depending upon whether the powder was against the bullet or the primer. This is utterly unacceptable for original BP guns in my mind.

w30wcf: excellent info once again!

Hobie: This topic comes up from time to time. It would sure save w30wcf, myself, and others having to re-post all this info if this thread was made into a sticky.
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Re: Pressure Spike in Smokeless Powders

Post by Borregos »

Hobie, I second the sticky idea. :D :D
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Re: Pressure Spike in Smokeless Powders

Post by J Miller »

KirkD wrote:Joe: I have found 5744 to leave a generous amount of unburnt powder unless capacity or near capacity loads are used, or unless filler is used. My capacity load of 5744 in the 44 Russian left little if any unburnt powder. Same with my filler loads. However, for my 45-60 I use 5744 in spite of the unburnt powder simply because 5744 is less position sensitive than, say, IMR 4227. Actual chronograph data showed a 200 fps difference with IMR 4227 depending upon whether the powder was against the bullet or the primer. This is utterly unacceptable for original BP guns in my mind.

w30wcf: excellent info once again!

Hobie: This topic comes up from time to time. It would sure save w30wcf, myself, and others having to re-post all this info if this thread was made into a sticky.
Kirk,

Towards the end of the pound of 5744 I tried CCI 350 mag LP primers. I forget the charge weight but it was higher than what Accurate calls for. It was from some other source. Using the mag primers gave me almost an acceptable burn. But not quite. I never tried a filler as I don't like those kinds of things.
To be honest, they bother me. Probably an irrational paranoia but it's there none the less.

I'm still hoping someone will give a 28% rule of thumb for a powder to use in the .45 Colt. I do have my reasons but they are too much to go into right now.

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Re: Pressure Spike in Smokeless Powders

Post by Old Time Hunter »

Prompted by this post, I contacted Hodgdon and specifically spoke to a guy named Mike (it seems that he is the only one working there, as this is has been about the tenth time I have called in some upteen years and he is the only one that picks up the phone!). Specifically I was looking for three questions to be answered: 1. Pressure spike curves of Pyrodex RS vs. BP vs. closest smokeless. 2. Alternative equivelant smokeless powders vs. BP. 3. Incomplete ignition of some powders.

Granted, I did not expect specific answers as I am sure that Mike did not want to incriminate nor open the opportunity for liability on Hodgdon's behalf. So that being said, here is what I got:

1. He does not know of any published data supporting the pressure spike curves of Pyrodex RS, but did say that it falls roughly between FFg and FFFg BP with a similar pressure rise, similar spike curve, and probably a little longer pressure curve (this probably is the reason that a 10% reduced load of Pyrodex is equivalent to a full load of FFg). He did say that ALL smokeless has a much faster pressure rise and sharp pressure spikes compared to BP (irrelevant as to Fg, FFg, or FFFg). This is what most likely makes smokeless dangerous in old BP guns as, according to Mike, older metallurgy lacks the elasticity to accomodate the quick expansion from the fast pressure spike of smokeless. This made sense to me when reading wcf30's post of equivalent performance with less pressure on his 420 grain .45-70 load. The general rule of thumb I was taught is that it takes approximately 10k of psi to cause intial movement of a properly seated projectile. The 4198 rises to the 10k much, much quicker than BP but still reaches it's peak of 13.5k psi much sooner than BP too. Therefore my conclusion is that the projectile reaches it's terminal velocity much quicker than the BP and the BP needs to have greater total pressure to achieve teminal velocity because of the slower acceleration.

2. Mike suggests using Trail Boss as a BP substitute in handgun cartridges. He suggested filling the case up to the base of a properly seated bullet, weighing the volume, then using 70% of that weight to start at. When queeried as to whether or not this could work on "original" black powder firearms, he referred to the fast pressure spike not being condusive to the older metal. On 2400 he evaded the question, probably because it is a competitors product, other than saying it wasn't too good. He did say that 4227 had the more correct burn speed, but said it was inconsistant in reduced loads. 4198 he did allude to as being the one most go to for the rifle cartridges as a subsitute to BP, which led me to the next question.

3. All the before mentioned smokeless have the propensity to yield incomplete combustion if the pressure is released before they have time to burn. In my Trapdoors, 28 grains of H4198 is not enough to create enough sustained pressure for complete combustion. This could be because of multiple factors such as: crimp, chamber size, or throat length...to name a few. Even your COL will have an effect on it as a bullet set farther out in the cartridge allows more space in the cartridge to allow less pressure.

This whole issue is a tight rope in getting enough pressure for consistant powder combustion and not too much pressure that it damages the gun. That being said, as wcf30 alluded to, millions have been using "lower" power smokeless for over a hundred years without hearing of failures. Just be carefull!
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Re: Pressure Spike in Smokeless Powders

Post by KirkD »

I am puzzled by a couple things Mike of Hodgdons said.

The first is his statement that all smokeless powder has a much faster pressure rise and sharper pressure spikes than BP. The chart I posted on the first page of this thread shows that Trail Boss has a much faster rise and a much higher and sharper pressure spike than BP, but the much slower burning SR4759 clearly has a much slower pressure rise and broader pressure spike. I also have Sherman Bell's article which shows a photograph of his results for IMR 4198, including five curves for IMR 4198, which shows a pressure rise pretty much identical to FFg (this is for a 40% BP load). Looking at those five curves, they certainly do not appear to rise 'much, much quicker'; they don't even appear to rise quicker at all than FFg. Mike's statement is also not consistent with observations that there are many slower smokeless loads that completely fail to obturate or 'bump up' a lead bullet whereas a compressed BP load does. Mike seems to indicate that he has not seen a pressure curve for Pyrodex RS, but estimates it is between FFFg and FFg. I am wondering if he has seen slower smokeless curves for BP cartridges, or maybe he is making his statements based on smokeless pressure curves that he has seen/measured for modern high pressure cartridges, which may well give very fast pressure rises due to their bottle neck construction coupled with very high pressure. It may be a question of comparing apples with apples. I would be willing to bet that the curve for IMR 3031 in a 30-30 sending a 150 grain bullet out the barrel at 2,250 fps rises much faster than IMR 3031 in a 45-70 sending the bullet out at 1,150 fps.

The key rule of thumb for anything I post on substituting smokeless for BP is that the substitution gives the same velocity as original BP velocities with ALL OTHER FACTORS THE SAME (i.e., same bullet weight, same case, same rifle) and that the smokeless powder is has a burn rate and relative quickness no faster than the Blue Dot/2400 region. This would be key in a discussion with Mike, as his statement above does not make sense within this context (at least for the five IMR 4198 curves that Sherman Bell has published for a 40% BP load), though it does make sense for modern high pressure applications and for fast smokeless powders. So I wonder if his statement is meant to be taken within the context of modern high pressure, bottle neck cartridges?

The second puzzling thing Mike said is that he recommended Trail Boss, which is an extremely fast powder with a very sharp pressure rise and a very sharp peak spike (see plot on page one of this thread). At the same time he indicated that H4227 has a more correct burn speed. There is a huge difference in relative quickness and burn rate between those two powders. I would tend to agree with Mike that IMR 4227 and 5744 (close in burn speed to H4227) all do well in the BP cartridges I have tried, but I'm pretty nervous about using Trail Boss in original BP guns because of the high peak pressure (as shown in the curves posted on page one of this thread). I do note, however, that Mike is hesitant to recommend Trail Boss for original BP handguns.

On a different topic, Old Time Hunter, I use 28 grains of IMR 4198 in my normal 45-70 loads under a 405 grain bullet, but I include a single sheet of toilet paper loosely rolled and folded. I found this significantly reduces E.S. and gives more consistent and complete burning.

The smokeless powders I personally use in old BP guns (which most of mine are) and find to work well, that give lower peak pressures than FFFg (for the same velocity, bullet weight, etc.) are:

For small cartridges (e.g., 38-40, 44-40, 45 Schofield, 44 Russian):
2400, IMR 4227, 5744

For rifle cartridges (e.g., 45-60, 38-55, 45-70, 45-90): IMR 4227, 5744, IMR 4198, RL-7 and IMR 3031

Pistol cartridges never require filler, but I find that rifle cartridges often do, particularly the larger ones like the 45-70 and 45-90. The reason for this is that the powders do not fill the case sufficiently to avoid large extreme spread, inconsistent burning and lots of unburnt powder. You can use slower powders to fill the case more, but then you get more unburnt powder. The proper filler solves all three problems. I've used toilet paper for years, and am now experimenting with COW. For COW, however, I recommend powders no faster than IMR 3031. You want to fill the case mostly with powder and only have 1/4" or less of COW filler. It is my opinion (intuitive) that if you have too much COW, you really reduce the case capacity, which really raises the pressure. For that reason, if 5744 does not work, or you don't want to use TP, use a slow powder such as IMR 3031 or IMR 4895, etc. and a small amount of COW. I NEVER use filler in a bottle neck case nor with fast powders. Filler is a pain, so I will work long and hard to find a load that does not require it. I'll even settle for slightly less accuracy (say 3" five-shot groups at 100 yards without filler rather than 1 & 1/2" groups with COW) rather than using filler. With COW, however, a fellow can use badly undersize bullets. An example is my Trapdoor with a .461 groove diameter. Without COW, my .457" 500 grain bullets wobble and give 8" groups. With COW I can get a 1" group (five shots) at 100 yards with the same undersize bullet (the mould I bought did not drop them as large as advertised so I'm stuck with it until I can get a larger mould). Filler does two things: first, it holds the powder against the primer, giving much better burning and, second, it acts as a great gas check.

I will experiment with different powders listed to see which gives me: same velocity as BP and good accuracy and no sooty cases. If those three conditions can be fulfilled with one of my powders and loads, then it becomes my standard load. However, things change between different old guns of the same caliber, so my loads don't work equally well in all the guns I have had of the same caliber, nor other people's guns. One other thing, I always start real low. I have found some published loads to be way too high (i.e., the same weight of powder and same weight of bullet, gives much higher velocities in a gun). That is why it is always wise to start low ...... I like to start about 20% below an average pressure, published load and chronograph the load to see if my velocities are matching the published velocities.
Last edited by KirkD on Thu May 20, 2010 2:59 pm, edited 3 times in total.
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Re: Pressure Spike in Smokeless Powders

Post by Griff »

Old Time Hunter wrote:Prompted by this post, I contacted Hodgdon and specifically spoke to a guy named Mike (it seems that he is the only one working there, as this is has been about the tenth time I have called in some upteen years and he is the only one that picks up the phone!). Specifically I was looking for three questions to be answered: 1. Pressure spike curves of Pyrodex RS vs. BP vs. closest smokeless. 2. Alternative equivelant smokeless powders vs. BP. 3. Incomplete ignition of some powders.

Granted, I did not expect specific answers as I am sure that Mike did not want to incriminate nor open the opportunity for liability on Hodgdon's behalf. So that being said, here is what I got:

1. He does not know of any published data supporting the pressure spike curves of Pyrodex RS, but did say that it falls roughly between FFg and FFFg BP with a similar pressure rise, similar spike curve, and probably a little longer pressure curve (this probably is the reason that a 10% reduced load of Pyrodex is equivalent to a full load of FFg). He did say that ALL smokeless has a much faster pressure rise and sharp pressure spikes compared to BP (irrelevant as to Fg, FFg, or FFFg). This is what most likely makes smokeless dangerous in old BP guns as, according to Mike, older metallurgy lacks the elasticity to accomodate the quick expansion from the fast pressure spike of smokeless. This made sense to me when reading wcf30's post of equivalent performance with less pressure on his 420 grain .45-70 load. The general rule of thumb I was taught is that it takes approximately 10k of psi to cause intial movement of a properly seated projectile. The 4198 rises to the 10k much, much quicker than BP but still reaches it's peak of 13.5k psi much sooner than BP too. Therefore my conclusion is that the projectile reaches it's terminal velocity much quicker than the BP and the BP needs to have greater total pressure to achieve teminal velocity because of the slower acceleration.

2. Mike suggests using Trail Boss as a BP substitute in handgun cartridges. He suggested filling the case up to the base of a properly seated bullet, weighing the volume, then using 70% of that weight to start at. When queeried as to whether or not this could work on "original" black powder firearms, he referred to the fast pressure spike not being condusive to the older metal. On 2400 he evaded the question, probably because it is a competitors product, other than saying it wasn't too good. He did say that 4227 had the more correct burn speed, but said it was inconsistant in reduced loads. 4198 he did allude to as being the one most go to for the rifle cartridges as a subsitute to BP, which led me to the next question.

3. All the before mentioned smokeless have the propensity to yield incomplete combustion if the pressure is released before they have time to burn. In my Trapdoors, 28 grains of H4198 is not enough to create enough sustained pressure for complete combustion. This could be because of multiple factors such as: crimp, chamber size, or throat length...to name a few. Even your COL will have an effect on it as a bullet set farther out in the cartridge allows more space in the cartridge to allow less pressure.

This whole issue is a tight rope in getting enough pressure for consistant powder combustion and not too much pressure that it damages the gun. That being said, as wcf30 alluded to, millions have been using "lower" power smokeless for over a hundred years without hearing of failures. Just be carefull!
Once again, the graph shows clearly why Trail Boss (IMO) is a POOR substitute for BP equivalency loads:
Image

That spike is tremendous. I have a full can of Trail Boss I won at a match... I'll be donating it back. I won't use it. While I like Hodgdon, and use their products, TB ain't one of them... IMO, it's sole redeeming feature is its' bulk... but that bulk costs... and at the price I pay for BP, it's more expensive to shoot. I can watch my Dillon and ensure I don't get a squib, without resorting to an expensive, boutique type powder. Unfortunately, Trail Boss ain't listed on this Powder Types & Burn Rate chart. Actually, I've always heard that BP burned faster than smokeless, but produces pressure slower. And that's true, outside of a container... where then you have to look at the individual powder.

And Joe, FWIW, in my experience, 5744XMP ain't so good in a pistol case. It really begins to shine in those big BP rifle cases, such as my .40-90SBN, or the .45-90 and up size cases. Surprisingly, it also works well in my .30-30 cases... but I'm still such a fan of RE-7 that I don't use it there.
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Re: Pressure Spike in Smokeless Powders

Post by Leverluver »

I've done my own pressure tests and seen the curves for myself and they agree with Kirk's. Well at least I know that if I ever have a question about powder pressures, there's one person I won't bother asking. There's certainly something that "Mike" doesn't know from a hole in the ground.
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Re: Pressure Spike in Smokeless Powders

Post by KirkD »

Griff wrote:And Joe, FWIW, in my experience, 5744XMP ain't so good in a pistol case. It really begins to shine in those big BP rifle cases, such as my .40-90SBN, or the .45-90 and up size cases.
I've had mixed results with 5744. Yesterday, I tried 5744 in my 44-40 (which I like to think of as a rifle cartridge, but it has the capacity of a pistol case). It gave roughly 6" five-shot groups at 100 yards, with lots of unburnt powder. On the other hand, my capacity load of 5744 in my 44 Russian gave pretty much zero unburnt powder. Since it was in an old sixgun, I didn't try any five-shot groups at 100 yards (heh, heh ..... I ain't no Elmer Keith). Two factors may be at play for pistol cartridges. One is whether it is a capacity load or not, and the other factor is that I think the pressure is too low to bump up a soft cast bullet well enough. In general, I find 2400 and 4759 work better in pistol cartridges, though I don't like the E.S. that 2400 gives me, and the 4759 is harder to meter accurately, so neither is a perfect powder. I've not tried Blue Dot.

By the way, I've not posted any range reports recently but that don't mean I haven't been there plenty. I'm working on load development for the 44-40 and 38-40 right now, but the kind of range reports I like to post are time-consuming and time is something I've not had a whole lot of, so I use what little I have for a trip to the range. That should change in a few weeks, however, and I look forward to posting some reports, probably when I settle on my 44-40 and 38-40 loads.
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Re: Pressure Spike in Smokeless Powders

Post by Old Time Hunter »

Kirk, I did bring up Sheman Bell's article and Mike's comment was "to my knowledge, Mr. Bell doesn't have the equipment to test pressure curves". His comments on TB sounded to me like a sales pitch, but he backed off when "original" black powder guns were mentioned.

Griff, you are correct as far BP is faster than most smokeless. But instead of a straight line to peak pressure, BP has a rounded bell curve to the pressure peak. Something about smokeless increasing pressure exponential mathematically when burning whereas BP can only explode as fast it can digest the oxygen in the nitrates and that is why BP is considered a "low" explosive because it deflagrates at subsonic speeds.

I wish someone would post corresponding scientific evidence with lab confirmation. I'd bet the military has it somewhere.
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Re: Pressure Spike in Smokeless Powders

Post by KirkD »

Old Time Hunter wrote:... Mike's comment was "to my knowledge, Mr. Bell doesn't have the equipment to test pressure curves".

..... BP has a rounded bell curve to the pressure peak. Something about smokeless increasing pressure exponential mathematically when burning ...
Well, I wonder why Mike would say that if he does not know for sure. The article I have by Sherman Bell, which is right here on my desk, has photographs of the test actual result print-outs for three different powders. One test was for a single round of Cordite, the other two show the plots for five pressure curves each for IMR 4198 and RL-7. In the article, Bell states that he used an Oehler Model 43 ballistic laboratory, with a signal from a strain gauge mounted over the chamber, one inch from the barrel face. I checked Oehler's site to see what that set-up does. It states, that it measures "Muzzle Velocity · Proof Velocity · Peak Pressure · Pressure Rise Time · Pressure Curve · Area Under Curve · Time of Flight · Velocity at Target · Ballistic Coefficient · Group at Target Accurate Ballistics". The key measurements in this case are peak pressure, pressure rise time, pressure curve and area under curve. It outputs a plot of the pressure curve for each shot. If five shots are taken, five pressure curves are plotted.

With regard to the bell shaped curve for slower smokeless powders: For a good idea of what the curves look like in Sherman Bell's photos accompanying his article, look at the bell shaped curve of FFFg on page one of this thread. The curve for IMR 4198 does not rise in a straight line. They trace out like a bell curve exactly like FFFg. They do not have a straight line rise. RL-7 is steeper, cordite has a broader curve.

All this to say that I do have some misgivings about some of Mike's comments. Sherman Bell does have equipment to do this stuff, even if Mike is not aware of it, and the smokeless curves for IMR 4198 look like FFFg but with a peak pressure lower than FFg. Even a medium speed powder like 4759 on the first page of this thread demonstrates a fairly flat bell curve type trace. I don't doubt that Mike knows some things about his company powders, but I wonder what he has actually seen in the way of pressure curves for the old straight-walled, large capacity black powder cartridges.
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Re: Pressure Spike in Smokeless Powders

Post by Sixgun »

All this scientific stuff is too much to take in. In my experience shooting tens of thousands of rounds for accuracy and velocity, with many dozens of different powders, in litterly hundreds of original BP rifles along with nickel steel classics from the 1895-1940 period over the last 38 years, this is what I have learned with the different powders available today.

1.) If your shooting big black powder cartridges with smokeless to approx. bp velocities or a bit over (1250-1600) with cast bullets, use 5744. Powders like RL-7, 4198, 4227, 4759, and 4227 also work but the velocity extremes will be more and sometimes erratic. Small extreme spreads=accuracy. Any slower powder will produce hangfires unless fillers are used. I ain't using fillers. Cold weather and other variables with give you lots of aggravation with bullets stuck in the barrel with slower powders.

2.) black powder cartridges (45-70) in STRONG modern guns using cast or jacketed with higher velocities are best with RL-7, 3031, 4198 or other powders of this burn rate that you have experience with. Will work in any weather.

3.) Smokeless cartridges of medium capacity (30-30, 30-06, 32 Spl.) with cast bullets at velocities slightly under factory (say 1600-1900) love 5744. Nothing else I have experimented with even came close to the small extreme spreads in any weather.

4.) Stay away from 5744 in handguns. It was never meant to be.

5.) If you like low velocities in any case, (900-1150) use Unique---loose in the case---burns clean with small extreme spreads---cheap to use :D

6.) Magnum primers are not needed with 5744 and will not make it burn cleaner. I have talked to ballisticians about this. Everything else gets standard rifle primers UNLESS I'm hunting in Colorado where the temps sometimes are in the negatives, then I use magnum primers with an extra grain or two of powder (RL-7)

In my experience, I have found you can get ANY powder to work in ANY case SOME of the time. Change the weather, bullet weight, alloy, different gun with a slightly larger bore, case position, hammer fall, and your GONNA have aggravation. 5744 NEEDS to be loaded to at least bp velocities in order to get clean burning and ignition. If you want to shoot slower velocities, use Unique. I have shot many thousands of rounds in original black powder rifles using Unique.---Just don't be stupid and double charge the case.

Revolvers never get used with anything slower than 2400 unless they are speciality cartridges such as the 454 or 357 Maximum. Unique will handle 100% of my needs from 750-1200 fps. Anything faster gets 2400.

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Re: Pressure Spike in Smokeless Powders

Post by KirkD »

Although I do not use Unique in anything other than my 45 ACP and my 25-20, the sheer number of fellows who use it in BP pistol cartridges and the success they have (such as Sixgun) is certainly making me want to live on the edge a bit and try it one of these days. Experience counts for a lot, and Sixgun has had a lot of experience. Sixgun, regarding the use of 5744 in pistol cartridges, I tend to agree. The only one it has ever worked well in is my 44 Russian, but it sure works well in the larger BP rifle cartridges.
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Re: Pressure Spike in Smokeless Powders

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Kirk, I am not trying to be contrary in any way, just repeating what I was told. Personally I pretty much stay to H4198 and Unique for straight wall BP rifle cartridges or pistols respectively. As far as using a filler...I ain't got the guts to do it. Years ago I saw a gent badly ring his barrel on a Martini using IMR4198 and a filler, scared the beegabbers out of me, looked like a snake swallowing a bowling ball.

Don't know the difference between IMR4198 and H4198 other than I get better consistancy on full boat loads in my .444 irrelevant to ambient temperature. Maybe I should try the IMR4198 for reduced loads and see how much unburned powder I get with that stuff. As I referred to earlier, my 29.5 grains of H4198 behind a 405-420 grain hard cast yields around 1400fps out of my oldest Trapdoor and leaves very few kernels. But I do not want to go any higher as I feel I am pushing the structural integrity of 136 year old metal.
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Re: Pressure Spike in Smokeless Powders

Post by KirkD »

Old Time Hunter, do you recall where the ring occurred in that gent's Martini? Also, I'd be interested to find out what kind of filler he was using. I'm not familiar with the Martini cartridge, does it have a good bottle neck on it? I have heard of one other person who ringed his chamber while using filler. I'm always interested to find out more details and try and figure out how it happened.
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Re: Pressure Spike in Smokeless Powders

Post by Old Time Hunter »

He had a 577/450, corn meal filler if I can recall, and it bubbled directly infront of the receiver. The casing had to be beat out of the chamber from the muzzle side. Claimed he only had about 30 grains of IMR 4198 in it.
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Re: Pressure Spike in Smokeless Powders

Post by Sixgun »

KirkD wrote:I'm not familiar with the Martini cartridge, does it have a good bottle neck on it? I have heard of one other person who ringed his chamber while using filler. I'm always interested to find out more details and try and figure out how it happened.
Kirk,
I have no massive amounts of experience on the fillers but from what I have read, the ring in a barrel happens when there is a wad over the powder, then air space between the wad and the bullet.

From the way you do it, it is the accepted way.

Like you said above, "was it in a bottleneck case". I believe thats where the problem comes in. :wink:

In all these years I have never experienced or read of a bad experience using Unique for reduced loads in BP cases (or any case) Its just a little dangerous as it ain't nothin' for a double charge. :o

I bet I have fired 10,000 rounds of 45-70 with 11 grains of Unique and a 385/405 Lyman. Virtually no kick with this 980-1050 load. :D Whenever I come across a "new" 45-70 rifle, I try this load in it. If it don't work, nothing else will. :wink: --------------------Sixgun
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.44-40 charge wt of early smokeless powder

Post by w30wcf »

Pop Watts wrote:OK, so I am still learning a lot here.

w30wcf, can I ask you what you believe to be amount of 4227 required to reproduce Black Powder ballistics in the 44-40 with 200 and 240gn projectiles? And, was there any velocity increase in the smokeless powder loads made for 1873 rifles over the BP loads?

Thanks, Pop.
Pop Watts,
The charge weight of DuPont Bulk Smokeless No. 2 was 17.0 grs. It filled the same space as 40 grs. of b.p.
W.R.A. CO. .44 W.C.F. headstamped cartridges used 200 gr. bullets.
U.M.C. .44-40 headstamped cartridges used 217 gr. bullets.
There were no early factory loadings with a bullet weight heavier than 217 grs.

U.M.C. was the only one to show a difference in velocity between b.p. (1,190 f.p.s.) and smokeless (1,235 f.p.s.).
That was prior to 1910. After 1910, catalog velocity was shown as 1,301 with no reference to the type of powder used.

17.0 / of my lot of H4227 under a 200 gr. cast bullet produced an average velocity of 1,287 f.p.s. That was with the powder positioned to the back of the case where it gave more consistant results.

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.44-40 ballistics

Post by w30wcf »

After 1910, ballistics of the .44 W.C.F. and .44-40 cartridges were cataloged at 1,301 f.p.s. with a 200 gr. bullet. "Sharpshooter" powder was used in 14 gr. charges to acheive that velocity. Cartridges were ok to use in b.p. firearms.

In the 1970's, factory velocity was lowered to 1,190 f.p.s., where it has remained to this day. Why? Because the factories decided to use a faster burning smokeless powder. The faster powder produced lower velocity at the same pressure as the slower burning smokeless. These cartridges are loaded not to exceed original b.p. pressures and thus are safe to use in b.p. firearms in good condition.

Here is a chart with information taken from a 1995 Hercules Reloaders Guide. Note the difference in velocities produced at the same pressure between faster and slower burning smokeless powders.

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Re: Pressure Spike in Smokeless Powders

Post by Wrangler John »

Where you can run into trouble is using slower ball powders with heavy deterrent coatings, like W-296/H-110 with starting loads, standard primers and a mild crimp. I know this from experience, the powder will partially ignite, pause and then reignite producing a hangfire and higher than normal pressures. This occurred in a .45 Colt. With magnum primers it worked well, but grabbing the wrong primers did the deed. A mass of plasticized powder fell out of the barrel after discharge, where it had melted producing a plug rather than burning. The manual publisher removed that load in the next edition.
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Re: Pressure Spike in Smokeless Powders

Post by Driftwood Johnson »

Howdy

I shoot a LOT of Black Powder. Mostly in 45 Colt and 44-40, but also in 45 Schofield. My 44-40 rounds are all shot in rifles, an original Winchester Model 1892 made in 1894, a Marlin Model 1894 made in 1895, a Uberti replica model 1873 and a Uberti replica 1860 Henry. My 45 Colt loads are shot in 2nd Gen Colts and Rugers.

Regarding Smokeless powders and old Colts: The Colt factory did not factory warranty the Colt Single Action Army for Smokeless Powder until 1900. This is all Smokeless powders, not just the old slow burning bulk powders. Rifles are one thing, but take a close look at the chambers of a SAA some time. There is only about .040 of metal separating one chamber from another at the narrowest points.

Early 1st Gen SAA production (1873) used materials similar to high grade malleable iron for both the cylinder and frame. Not modern steel. Around SN 96,000 (mid 1883) Colt began using low/medium carbon steel. However these guns were not factory warrantied for Smokeless. Around SN 180,000 (mid 1898) Colt began using medium carbon steels, but these guns were still not factory warrantied for Smokeless. By 1900 Colt had gotten a better handle on heat treating these steels and felt confident in factory warrantying the SAA for the Smokeless Powders of the day. In 1901 Colt began placing a VP in a little triangle on the trigger guard for Verified Proof as an indication that the model was OK to use with Smokeless Powder. But Colts made prior to 1900 should not be fired with Smokeless Powder. Period. This information is from Kuhnhausen's Colt Single Action Revolvers Shop Manuals. As for other revolver manufacturers, it is doubtful they had access to any better metalurgy than Colt did. I would use the 1900 date as a good rule of thumb.

Here is the Verified Proof mark for Smokeless on one of my Colts. If Colt thought it was important enough to include this, then who are we to argue with them? Mike Venturino concurs and will not shoot his old Colts with Smokeless. Part of the problem is that most shooters don't want to mess around with Black Powder and the clean up involved, but I do it all the time and it is not at all as onerous as most shooters think. If the VP mark does not appear on an old Colt, the shooter is taking a chance shooting it with Smokeless loads, unless it was made in 1900, the year before the mark began appearing.

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Very generally speaking, rifles are going to be a different story. For the most part you are not dealing with the tiny cross sections of steel to contain the pressure that you are with a revolver cylinder. I certainly do not hesitate to shoot Smokeless 44-40 rounds in my old '92 and Marlin. Mostly Unique. But these guns are a very strong design, the chambers have plenty of steel surrounding them, and the bolt locking mechanism is very strong. I also do not hesitate to shoot Smokeless in my Winchester Model 1897 Shotgun, made in 1908, but they were proofed for Smokeless powder anyway. The modern steel of the Uberti rifles makes me completely confident in their strength.....HOWEVER, they are still toggle link actions, so I would keep my Smokeless 44-40 pressures down to SAMMI specs, and not go over that. Around 13,000 cup.

Here is a pair of pressure curves superimposed on each other that are illustrative of what we are talking about. This illustration was sent to me a number of years ago by a ballistics engineer. The curves in question are for shotgun loads, both producing 1200 fps with 1 1/8 ounces of shot. Pressure is expressed in PSI, time is in milliseconds. Sorry, I have no information about the specific Smokeless powder used, undoubtably it was a relatively fast burning shotgun powder. The BP is FFg Goex. But what is illustrated here is how the Smokeless curve is not only much greater in pressure, but also much shorter in duration. This sharp pressure spike is what we are talking about when we say that older steel may not have the elasticity needed to survive the sharp pressure spike of Smokeless powder. Notice how the BP pressure curve is not only lower in amplitude, but it is much gentler, spread out more over time.

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Re: Pressure Spike in Smokeless Powders

Post by w30wcf »

Driftwood Johnson,
Thank you for your input. I do know that Colt did not advise the use of smokeless cartridges early on, but I wonder if it was because of the uncertainty of the type of smokeless and the amount of smokeless being used by reloaders?

The graph in your post was certainly of fast burning shotgun powder. The "low pressure smokeless" used in the early smokeless cartridges (DuPont No. 1 & DuPont No. 2) would have had a much more gradual pressure spike like this graph shows which compares b.p / 4759 (similar in burning rate to DuPont No. 2) / too fast burning smokeless for b.p. (Trail Boss) similar in pressure rise to your graph.

The rise is in milliseconds. The higher the value, the slower the rise.

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Re: Pressure Spike in Smokeless Powders

Post by Driftwood Johnson »

Driftwood Johnson,
Thank you for your input. I do know that Colt did not advise the use of smokeless cartridges early on, but I wonder if it was because of the uncertainty of the type of smokeless and the amount of smokeless being used by reloaders?
No, it was because Colt felt the metal was not strong enough for the pressure involved with Smokeless powder. Period. No firearm manufacturer tailors his product to reloaders. Instead, they tailor the product to be safe with commercially available ammunition. Firearm manufacturers had no more control of what went into homemade reloads in 1899 than they do today. Manufacturers must rely on the specifications of ammunition made by commercial ammunition manufactured under closely controlled conditions. That was no different in 1873 or 1899 than it is today. Colt simply knew the metals they were working with were not up to the pressures developed by Smokeless powders of the day, considering how thin the cross section of the cylinders were/are. As I said earlier, rifles are a different story, they are more heavily built than a revolver cylinder, which afterall is the pressure vessel in a revolver, not the frame. That's why they finally stamped a Smokeless proof mark on the SAA in 1901, because they knew they had achieved the strength needed in their steel to safely digest commercially loaded Smokeless ammunition.

Yes, I know the curves I posted are not the same as powders that may simulate Black Powder pressures more closely. I posted them as an illustration of the difference in pressure curves between most Smokeless powders and Black Powder. Shooters who are completely unfamiliar with the difference between Smokeless and Black Powder curves find these graphs very useful.
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Re: Pressure Spike in Smokeless Powders

Post by KirkD »

Driftwood Johnson wrote: Yes, I know the curves I posted are not the same as powders that may simulate Black Powder pressures more closely. I posted them as an illustration of the difference in pressure curves between most Smokeless powders and Black Powder. Shooters who are completely unfamiliar with the difference between Smokeless and Black Powder curves find these graphs very useful.
It would not be correct to state that the shotgun smokeless powder smokeless curve that you posted represents most smokeless powders. There is a great deal of confusion about the burn rates of smokeless powders, which range from much faster than BP (with a much higher pressure spike) to much slower than BP (with a much lower pressure spike). As I posted earlier, we are talking about medium speed smokeless powders that have the same pressure spike as BP or lower. Shotgun powders should not be used. We all really need to quit talking about smokeless powders as if they were all the same. They are not the same; they span a very large range of burn rates that includes the same burn rates of the various BP powders.

Regarding using smokeless powders in First Gen Colts and early S&W Top Breaks, such as the Schofield, if a fellow knows what he is doing, smokeless is safer than BP. Medium speed smokeless powders like 5744 or 4759 or 2400 that are loaded to give the SAME velocity as BP for the same cast bullet are preferable to BP. They give a lower pressure curve for the same bullet weight and the same BP velocity. I own, or have owned, and shot original Colt SAA's, as well as original S&W Schofields, 2nd Model Americans, and New Model #3's. I prefer to use smokeless in them for two reasons: First, it is safer, given the lower pressure spike. Second, it is easier on antiques to use smokeless when it comes to making absolutely sure that every bit of BP fouling is out of every single micro-pit.

CAUTION: The primary danger with using medium speed smokeless powders such as the ones I mentioned above in BP cases is using too much. Fellows who don't know what they are doing, or who don't understand the different burn rates of smokeless powders, or who can't work up a load to match original BP velocities should stick with BP. One way around this is to develop a capacity load of the right medium speed smokeless powder, which I have done for both the 44 Russian and the 45 Schofield.

ANOTHER CAUTION: When developing a smokeless load for an old sixgun, the cylinder to forcing cone gap must be within factory spec. If it is not, you will loose pressure and get a lower velocity. If you are chronographing the load to match original BP velocities, you will get too high a pressure in the cylinder if your gap is too large, since your chronographed velocity will be post-gap pressure loss velocities. The safest way to develop a smokeless load is to first chronograph at least 5 BP shots with the identical gun. Then develop your smokeless load to match the same velocity using a medium speed powder such as 4759 or 5744. I personally prefer not to use 2400 because of its extreme spread for many cartridges. I actually developed a capacity load of IMR 4198 for my original Schofield.

BP has two advantages:

1. More fun to actually shoot
2. You can't overfill the cases very easily

Smokeless has two advantages (assuming you know what you are doing):

1. lower pressure spike if medium speed powders are used
2. if you happen to leave a minute amount of residue in some microscopic pit somewhere, it won't matter
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Re: Pressure Spike in Smokeless Powders

Post by w30wcf »

Driftwood Johnson,
Thank you for your further explanation. What Colt might have not known at the time was that the pressure of DuPont No. 2 was no greater than b.p. and possibly even less. Anyway, it is an interesting subject. Regarding " I posted them as an illustration of the difference in pressure curves between most Smokeless powders and Black Powder.", "most" would not be entirely correct. That would only apply to smokeless powders with a burn rate faster than 2400. There are many more powders with slower burn rates than 2400.

Kirk,
Thank you for your educational post on your experiences.

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Re: Pressure Spike in Smokeless Powders

Post by Driftwood Johnson »

2. if you happen to leave a minute amount of residue in some microscopic pit somewhere, it won't matter
Actually, if you leave a little bit of BP fouling in the pits of an old bore, but liberally coat it with oil, like Ballistol, it will not matter either. Black Powder fouling is no where near as corrosive as most shooters think. Part of the problem was the old corrosive primers that were common in the BP era. We don't use corrosive primers anymore, so that problem has gone away. Black Powder fouling is extremely dry, and will wick moisture out of the air. It is this moisture held close against the steel that can cause corrosion. But if the fouling is soaked with oil, it can no longer draw any moisture out of the air. Think of a sponge that is already soaking wet. It won't take on any more water.

I have been shooting Black Powder in C&B revolvers since 1968. A lot has changed since then. When I decided to start shooting BP in Cowboy Action, I too was afraid to use it in the 100 year old, pitted bores of my old Winchester 1892 or Marlin 1894. I had read that it would require a lot more elbow grease to remove all the fouling from the thousands of tiny pits. So I bought a brand spanky new Uberti 1873 with a nice shiny bore. I have a Uberti 1860 Henry too, with a brand spanky new shiny bore too. Neither gun has ever seen any Smokeless ammo since I have owned them. But occasionally I will bring the old Marlin or the old Winchester to a match. As I said earlier, after a good scrubbing with my favorite water based BP fouling I run a patch soaked with Ballistol down the bore. I follow up with a dry patch to remove most of the Ballistol, but a good coating gets left behind. The Ballistol does its job of soaking into whatever BP fouling is left in the pits, and prevents any further rust from happening.
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