Burn rate of powder.....

[hightime]

Doesn't it make sence to use a slower burn rate in a long rifle barrel and a faster in a pistol or short rifle?
My 24'' rifle barrel seems to be tight near the chamber then open up towards the muzzle. I'm going to try a slower burning powder and see if the longer burn will better seal the bullet in the second half of it's barrel travel.
I tried the other way with Trail Boss and didn't like it. I think that will work good in the pistols.

Owen

[Blaine]

You'll know by the unburnt powder, and dirt... (flame suit on) published loads, though

[J Miller]

Naw, try 35grs of 3F black powder and a Lyman 454190 filled with SPG and it will work great.


Seriously, I've tried IMR 4227 and Hogdgens 5744 and both of them leave lots of unburned kernels of powder in the barrel and action. You've got to push them up to Ruger level loads using a mag primer to get any kind of cleanliness from them.

Now, I don't mind soot or that oily goo left behind by some bullet lube - powder combos, but I draw the line at getting showered with unburned powder every time I eject a fired case. And that is what happens when I use these types of powders in standard pressure .45 Colt loads.

Joe

[Hobie]

Doesn't it make sence to use a slower burn rate in a long rifle barrel and a faster in a pistol or short rifle?
My 24'' rifle barrel seems to be tight near the chamber then open up towards the muzzle. I'm going to try a slower burning powder and see if the longer burn will better seal the bullet in the second half of it's barrel travel.
I tried the other way with Trail Boss and didn't like it. I think that will work good in the pistols.

Owen

I love this sort of question which has been oft discussed here.

Faster powders will better "bump up" the bullet base (we're talking cast bullets here). That's one reason to use them. Slower powders don't bump up the bullet further down the bore, what happens is the bullet goes through the tight portion and then is too small for the big portion of the barrel further down.

If you're concerned about ballistic performance my experience is that generally what gives the best velocity in one length barrel in a given cartridge will do the same in any other length barrel. Yes, there are exceptions, there are always exceptions but they call them exceptions for a reason.

If you don't like something that's just fine. There's lots of reasons one prefers one powder over another and it doesn't need to be logical. One guy told me he preferred one particular powder in one particular cartridge because of how it smelled after firing. Be glad you live, for now, in a country that offers you so many choices.

[jager3]

Hightime - I have recently settled on SR4759 in my 1873 Short Rifle. My best load is 17.0gr with a Lee 255FN cast with no "blow by" or discernible leading and is a Lyman "book" load. I'm "clocking" right at 1375 (+ or - 8fps). I'm also using WLP primers and Starline brass. I've also had good accuracy with 18.8gr/IMR4227, but lower velocity; and 16.5gr/2400, but greater velocity "spreads" and a bit "dirtier" barrel (yeah, I know it can't compare to BP ).

[hightime]

Well my replacement gun came and I sent it right back. I'll get to try some of these things in a week or so.
Thanks Hobie, is what your saying it's better to bump up the bullet early. I was thinking that I needed it to expand a bit down the barrel, at least with the gun I had. But what I think I understand from you , I might not get that good fit if the burn rate is slower.
I just came in from loading twenty rounds of slower burn. I probably wasted my time.... No way, it's all fun.

jager3, I'm seeing variations in Uberti barrels. I would think that's why one load works for some and not others.
I'm sure some are saying ''Da''.
Owen

[Griff]

There are many variables in such a calculation. There are several "rules-of-thumb", but no real "cast-in-concrete" solutions.

I was taught, and subsequently verified by experimentation (for a couple of my guns), that to obtain maximum velocity, the adage that slow powders in long barrels will yield higher velocities with lower pressures. However, they may not always yield the best accuracy. Quick burning powders may exhibit similar paradoxes in short barrels.

I use a lot of RedDot in my .45Colts, that's after using 231, Unique, #2, Clays, and a couple of others (well, ok... maybe up to a ½-dozen others).

Back several years... maybe 18 or 19, I wrote to Accurate and asked them for load data with 5744 for the following cartridges: 12 ga., .30-30, .45 Colt, & .40-90SBN with specific bullet weights I then currently used. They gave me the data, then said something along the lines of, "... you will probably not be happy attempting to use these loads in a couple of your cartridges." And I wasn't, although I admit, I never tried it in the shotgun. 5744 has its uses in big voluminous rifle cases of the BP era... not the relatively smaller pistol cases.

Although I use a fairly light load, (6.5 grs.) of RedDot in my .45Colt, I'm loading it mostly for CAS and lighter than traditional bullets. It gives excellent accuracy and I've had not issues with positioning or temperature, unlike what some other powders exhibit in light loadings. I have worked up heavier loads, and accuracy didn't suffer, but recovery time from recoil increased, and that's not conducive to performance in timed events.

[6pt-sika]

Faster powders will better "bump up" the bullet base (we're talking cast bullets here).

"Obturate" is the word you may have been looking for !

[6pt-sika]

Now on the other hand , if your bullet is large enough to fill the bore "obturation" is not as important .

Just today I fired some 444 loads for SubSonic using the RD 432-300GC as well as my MM/RD 432-325GC bullet . Both pushed with TrailBoss . Both did okay for what I was wanting although not tack drivers by any stretch .

[6pt-sika]

Back several years... maybe 18 or 19, I wrote to Accurate and asked them for load data with 5744 for the following cartridges: 12 ga., .30-30, .45 Colt, & .40-90SBN with specific bullet weights I then currently used. They gave me the data, then said something along the lines of, "... you will probably not be happy attempting to use these loads in a couple of your cartridges." And I wasn't, although I admit, I never tried it in the shotgun. 5744 has its uses in big voluminous rifle cases of the BP era... not the relatively smaller pistol cases.

I used XMP5744 for several years in a broad spectrum of cartridges with cast bullets for hunting , silhouettes and paper .

Think the smallest I used it in was the 25-36 Marlin and the largest was the 45-70 .

My go to silhouette load for several years was 22 grains of XMP5744 with the Ranch Dog 311-165GC .

Using 5744 with cast I killed deer using the following cartridges . 30-30 , 32 Special , 356 WIN , 375 WIN , 38-56 , 40-65 , 444 and 45-70 . IF I hadn't gone overboard and started messing with the heavyweights in the 444 and 45-70 I'd most likely still be shooting mostly 5744 with cast . But once you get to a certain projectile weight in both cartridges you need to push uhm fast to make uhm stabalize or thats been what I've found to be true !

[Don McDowell]

Alot depends on powder capacity and bore ratio of the case, the shape of the case and the weight of the bullet.
But assuming in this example we're talking about a 45 colt, 44wcf or similar, you'll be hard pressed to find better powders for velocity and accuracy than bludot,2400, and 5744. Unless of course you do the cartridge proper and just go with a good 3f blackpowder.

[hightime]

Don, I'm going to take a look at the burn rates of those, my books are out in the shop, but I'm thinkin' all those are middle of the chart. I don't have Blue Dot. I do have some 2400 and IMR 4198.
I have to go get my another 45 rifle, so when one is away the other can play.

Owen

[Cliff]

If this gun,rifle, or handgun is tight infront of the chamber in the barrel itself, you will probably want to lap or polish the tight spot out. A lot of todays guns are crush fit on the barrel to the frame. Squeezes the barrel a bit. A qood quality barrel will be tapered from chamber to the muzzle, just a slight reduction, common of some european rifles, 22's and such. It was common at one time for custom barrel makers to lap their barrels to achieve this effect. Todays production demands make it hard to be done right. There may be another way which is to relieve the rifling the length of the restriction if it is not all that long. A good reamer can smooth it out until it matches the rest of the barrel. But once the bullet passes the restriction the pressure pushing it is going down and no bumping or obturation will happen.
You may need a good cast of the barrel immediately at the chamber end of the barrel, cerrosafe is best and works well if used as intended. Almost all powders whether slow or fast rated is usually comsumed in the cartridge case before the bullet leaves the chamber. Powder depends on pressure to burn properly, once the pressure drops the powder fizzles more or less. Just Saying. All the best in your search.

[Hobie]

Faster powders will better "bump up" the bullet base (we're talking cast bullets here).

"Obturate" is the word you may have been looking for !

He used "bump up" so I did too. I'm trying not to confuse him further.

[Hobie]

If this gun,rifle, or handgun is tight infront of the chamber in the barrel itself, you will probably want to lap or polish the tight spot out. A lot of today's guns are crush fit on the barrel to the frame. Squeezes the barrel a bit. A good quality barrel will be tapered from chamber to the muzzle, just a slight reduction, common of some European rifles, 22's and such. It was common at one time for custom barrel makers to lap their barrels to achieve this effect. Today's production demands make it hard to be done right. There may be another way which is to relieve the rifling the length of the restriction if it is not all that long. A good reamer can smooth it out until it matches the rest of the barrel. But once the bullet passes the restriction the pressure pushing it is going down and no bumping or obturation will happen.
You may need a good cast of the barrel immediately at the chamber end of the barrel, cerrosafe is best and works well if used as intended. Almost all powders whether slow or fast rated is usually consumed in the cartridge case before the bullet leaves the chamber. Powder depends on pressure to burn properly, once the pressure drops the powder fizzles more or less. Just Saying. All the best in your search.

Good points Cliff and well said. Saved me some typing, too!