Bolt Thrust Experiment #3 .22 LR & .44-40

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Bolt Thrust Experiment #3 .22 LR & .44-40

Post by w30wcf »

.22 L.R. - 24,000 SAMMI MAP
Case head pressure = 831.3 p.s.i. ( .210" heel dia. x .5 = .105 x .105 x 3.14 x 24,000 psi)

I just did not feel that there is anything even remotely close to 831.3 lbs of bolt thrust.
If there was, my Ruger semi auto pistol would likely have shot loose many rounds ago.

First I tested the amount of resistance the bolt / hammer provided to keep the action closed.
The resistance registered 16# on the scale.

I loaded 3 rounds of Federal Auto Match .22 L.R. (1,200 f.p.s. 40 gr. bullet) and placed the bolt
against the scale and preloaded it to 16#.

Those 3 rounds developed an average of only 20# of bolt thrust. I was expecting more..........

Obviously, the thin case provided plenty of grip against the chamber wall.....

This weekend - .44-40 ..........


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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by BuckRimfire »

Any engineers around who can calculate the yield strength of a .22LR cartridge rim? Implicit in your hypothesis is the requirement that the rim be able to bear briefly something like 800 pounds in tension without deforming much.
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by rbertalotto »

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Nath »

w30wcf wrote: .22 L.R. - 24,000 SAMMI MAP
Case head pressure = 831.3 p.s.i. ( .210" heel dia. x .5 = .105 x .105 x 3.14 x 24,000 psi)

I just did not feel that there is anything even remotely close to 831.3 lbs of bolt thrust.
If there was, my Ruger semi auto pistol would likely have shot loose many rounds ago.

First I tested the amount of resistance the bolt / hammer provided to keep the action closed.
The resistance registered 16# on the scale.

I loaded 3 rounds of Federal Auto Match .22 L.R. (1,200 f.p.s. 40 gr. bullet) and placed the bolt
against the scale and preloaded it to 16#.

Those 3 rounds developed an average of only 20# of bolt thrust. I was expecting more..........

Obviously, the thin case provided plenty of grip against the chamber wall.....

This weekend - .44-40 ..........


w30wcf
I am absolutley not surprised what so ever.....thanks all the same. Time....no time! Nearly!

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Model 52B »

w30wcf wrote: .22 L.R. - 24,000 SAMMI MAP
Case head pressure = 831.3 p.s.i. ( .210" heel dia. x .5 = .105 x .105 x 3.14 x 24,000 psi)

I just did not feel that there is anything even remotely close to 831.3 lbs of bolt thrust.
If there was, my Ruger semi auto pistol would likely have shot loose many rounds ago.

First I tested the amount of resistance the bolt / hammer provided to keep the action closed.
The resistance registered 16# on the scale.

I loaded 3 rounds of Federal Auto Match .22 L.R. (1,200 f.p.s. 40 gr. bullet) and placed the bolt
against the scale and preloaded it to 16#.

Those 3 rounds developed an average of only 20# of bolt thrust. I was expecting more..........

Obviously, the thin case provided plenty of grip against the chamber wall.....

This weekend - .44-40 ..........


w30wcf
Using the base diameter of the case and a resulting .115" radius, I get and area of .0415 square inches and 996 pounds acting on the bolt.

Adhesion of the case wall is one factor and you could try to control for it by reducing adhesion by oiling the case wall liberally before chambering the round. It won't be perfect, but you might see an increase.

Similarly, I suspect the lubricant all over the cases of SK .22LR ammunition probably reduces the case wall adhesion, and you could test that with lubed rounds and with ammo from the same lot with the lubed wiped off.

---

But….I think what's missing from your experiment is the effects of:

1) inertia and the amount of energy required to start the mass of the bolt in motion before it can even begin to start acting against the scale, and

2) the concept of "work" where work equals force times distance.

----

Consider the five Rocketdyne F1 engines in the S-1C first stage of the Saturn V rocket used to launch the Apollo moon missions. They each generated 1,522,000 pounds of thrust for a total of 7,610,000 pounds of thrust, when the Saturn V rocket as a whole weighed about 6,200,000 pounds. That's an excess of 1,410,000 million pounds of thrust on the pad - yet if you saw a launch or a video of a launch, you'll recall the rocket did not jump off the pad like it just got hit with 1.4 Million pounds of thrust. It started up with a very stately and almost imperceptible motion at first.

That was due to the inertia of the rocket itself, and it took a lot of time and distance for that excess thrust to accelerate the rocket to high speeds. That was even with the excess thrust constantly increasing as the five F1 engines burned a total of 28,410 pounds of fuel each second of the 161 seconds of burn time. By the latter part of the burn, the excess thrust was huge - so huge and they shut down the center engine 26 seconds early to limit acceleration. But it's the over all time and distance the thrust was applied that was important as while the first stage got the rocket to 7,500 fps, it took 161 seconds and a distance of about 71 miles to do it.

That potential for rockets to produce high thrust over long periods of time is also why we launch space craft with rockets rather than great big cannon - as we'd need a really long barrel to maintain the acceleration long enough to achieve orbit or escape velocity and/or we'd need some truly immense pressures that the space craft and astronauts would never survive.

To put that in perspective, a fuse in an naval shell has to be built to survive on the order of 10,000 Gs and that's just to get it into the 2600-3000 fps range in a barrel perhaps 20ft long. It's not even close to the 25,800 fps we'd need to achieve orbit. People can only tolerate around 32-45G for very short periods of time before they start suffering permanent injury and turning to goo, so launch via cannon is just not an option - no offense to Jules Verne intended.

----

The same force times distance = work principle applies to a blow back operated rifle. The pressure acting on the case head and bolt face has to overcome of the mass of the bolt in a rifle along with any mass you have to put into motion in the measuring device and get it onto motion before you'll see any reading on your scale - and it has a very short time to make that happen. If a .22 LR reaches 1280 fps in a 16" barrel, and we assume the average velocity in the barrel is around 640 ft per second, it's only going to be in the barrel for about .002 seconds. We can even be generous and double that to .004 seconds and see that we won't get a whole lot of work done in that very short period of time. And we also know that the peak pressure of 24,000 psi won't last nearly that long, so we don't even have the 996 pounds of thrust available for all of that very short time.

Like a rocket, the actual "work" done to move the bolt is determined not just by the peak pressure (thrust) on the case head and bolt face, but also the length of time it presses on the bolt face. Similarly, the distance the bolt moves, the velocity it is able to achieve and the kinetic energy it gains in the brief time available is also fairly low.

So while 831 pounds or 996 pounds sounds like a lot of pressure, the amount of "work" it can do in a rifle is pretty small as it acts on the bolt for such a short time, and the velocity and kinetic energy the bolt develops is low.

For a different and maybe simpler gear head/non rocket science example, consider a piston engine. The power depends on the swept volume and mass flow of the engine and two of the big players there are bore diameter and compression ratio, but neither of those matter unless there is some piston stroke - the distance over which that pressure acting on the piston is applied. It's the stroke and the RPM combined with the compression and bore diameter that makes the car go fast.

To put it in those automotive terms then, you may have 996 pounds of pressure in the combustion chamber, but it's very brief pressure acting over a very short "stroke" in your rifle's "engine", producing very little "power."

But that small distance and the bolt velocity that is developed in that short distance is still enough to cycle the action in a blow back .22LR.

----

The firearms designer takes the mass of the bolt, as well as the energy absorbed by the recoiled spring and hammer spring as the action is re-cocked to get the right amount of bolt velocity and kinetic energy from the brief impulse from chamber pressure to cycle the weapon.

That's why you see aluminum slides and small recoil springs on most .22LR 1911 conversion kits - they need to reduce the mass of the slide and the force of the spring to get it to operate with the limited impulse available from the .22 LR.

Conversely, On the original 1911 slide, with the delayed blow back principle, they need a heavy slide to delay the rearward motion of the slide in order to in turn delay the unlocking of the action until the pressure has dropped to near zero. And again, from that point onwards, it's the mass of the slide that is now in motion that re-cocks the hammer and compresses the recoil spring, so that it can reload the chamber and return the slide to battery.

Similarly, you can take a blow back operated sub machine gun with a fairly low cyclic rate like the Uzi, and lighten (reduce the mass) of the bolt to increase the cyclic rate. Less mass, less inertia results in more bolt velocity. Properly sprung, that then results in a higher cyclic rate.
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Nath »

woohoo I think I saw time mentioned in that last text :lol:

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Geeze Model 52, I could have told you that. I thought this was knowledge we all should know!

On a serious note, well, to say the least, I'm impressed.

Thank you for taking the time to post all of that. Some of it sank in, but most was over my head. Overall, I did learn something, especially with the way you described how the rockets work and why you can't just "shoot people out of a gun". (now I have to reread this about 4 times)




Jack Sr.--Thanks pard. Will be looking for the 44-40 results. I'm headed for Hamburg tomorrow for a long range buffalo match. These things I can understand.-----------6
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by AJMD429 »

Some of this gets into things like why an arrow from a compound bow can kill a deer faster than a bullet from a gun, and why a baseball bat might be more lethal than a 25 ACP.

Fascinating...!
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by BuckRimfire »

Getting 3 tons of LOX and kerosene into each engine EVERY SECOND is about as impressive as anything else about Apollo that I can understand (which ain't much).
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Old Savage »

Once again, It is not the base diameter of the case, read Lilja.
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Ben_Rumson »

Well phooey... I was hoping John had posted on the 44-40 test by now.. hope all is well
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by w30wcf »

Ok, finally had a chance to test the .44-40 ....... a few days later than anticipated. Life gets in the way sometimes .......

Anyway, the test indicates that the case head did not make contact with the bolt.

I used 2 cases with thinned rims (front) allowing for .015" headspace.
I seated the primers to stand .012" proud of the base of the case then applied 2 small clay pads on either side of the primer to the same .012" thickness.

Cases were loaded with 6.5 / Trail Boss / 215 gr cast bullet. Pressure 13,000 CUP or thereabouts.

Result:
Primer protruding .010" . Clay pads the same. No evidence that the case head touched the bolt since the small clay pads were not distorted as they would have been if the case head touched the bolt face.

I will say that the cases used were not full length sized. Just neck sized as I do all my .44-40's with a special die.

I'll post a pic in the next day or so.

52B,
Good points. I understand what you are saying. In this case, as it turned out, the primer pressure of approx. 65#'s (.08" flash hole / 13,000 cup) was enough in combination with the cartridge lock in the chamber to keep the case head from contacting the bolt.

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Nice going Jack! This is going to be interesting.

Beings that you already have the brass turned down............keep going, a half grain at a time.

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by rogn »

Would those doing the math on the rim fires please recheck their decimal points.
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Grizz »

Thanks 52 for the details.

I read the orions hammer article carefully and think he missed a detail. He was stating how heavy the bolt has to be to retard the cycle, and then showed 45/70 stats. The locked breech 45/70 essentially has a bolt weight equal to the gun weight.

The HK blowback operated rifle has a massive bolt carrier zooming back and forth, adding to the bolt weight. In that example the case is floated with gas pressure to keep it from sticking in the chamber the way the 44-40 case did.

All very interesting stuff.
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Ben_Rumson »

I'm not surprised at all... Thanks John very cool 8) 8) 8) 8) 8)
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by JimT »

Forgive me if it has already been mentioned, but you all might go back and read P.O. Ackley's tests shooting the .30-30 Model 94 Winchester with the locking lug removed and the bolt held closed by finger pressure only. I believe he used oiled and dry cartridges to show the difference ..
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

w30wcf wrote:... Pressure 13,000 CUP or thereabouts... No evidence that the case head touched the bolt since the small clay pads were not distorted...

... In this case, as it turned out, the primer pressure... was enough in combination with the cartridge lock in the chamber to keep the case head from contacting the bolt.
Now that I certainly did not expect.

As for the primer pocket, the pressure is higher inside the pocket while the primer compound is burning (and thus pushes the case forward), but it is roughly equal on both sides of the flash hole later, so it shouldn't much affect the thrust on the base of the case.

Excellent experimental stress analysis you've done. I wish I could explain the outcome. I do expect case cling to reduce the breech thrust but not eliminate it (except for unusual instances).
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Jim,
You missed it last week. Check out this thread. Model 52b and Buck Elliot seems to have disproved it.-----6

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Nath »

Thanks and I am one of the few not surprised.
As said by me many times, time! There is not enough time for the pressure to give momentum to the case to the level of calcs come to! Time is the element missed or ignored!

Using a blow back auto as an argument for huge bolt loading is a red herring. Most slugs have left the barrel by the time the action cycles. In fact it is a function of the bullet leaving the barrel that alows the pressure to drop enough to allow the case to let go of the chamber wall.

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

Nath wrote:There is not enough time for the pressure to give momentum to the case to the level of calcs come to! Time is the element missed or ignored!
Au contraire!

Using QuickLoad, one gets an estimate of the average pressure (about 4000 psi) and the time the bullet corks the barrel (about 2.3 msec). A .44-40 case weighs about 100 gn. A conservative estimate of the case ID would be 0.40 inches. A back of the envelope calculation says the case should travel some 3 feet in those 2.3 msec (had it not cleared the chamber); that's a wee bit more than the 0.017 max headspace slop SAAMI calls for. Clearly there's ample time for the pressure to close the headspace gap.

Obviously, case cling slows it, but I'm still mystified by the results of w30wcf's nice test. Someday, if I find one, I'll have to section a .44-40 case and make further back of the envelope calculations.
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Nath »

KWK wrote:
Nath wrote:There is not enough time for the pressure to give momentum to the case to the level of calcs come to! Time is the element missed or ignored!
Au contraire!

Using QuickLoad, one gets an estimate of the average pressure (about 4000 psi) and the time the bullet corks the barrel (about 2.3 msec). A .44-40 case weighs about 100 gn. A conservative estimate of the case ID would be 0.40 inches. A back of the envelope calculation says the case should travel some 3 feet in those 2.3 msec (had it not cleared the chamber); that's a wee bit more than the 0.017 max headspace slop SAAMI calls for. Clearly there's ample time for the pressure to close the headspace gap.

Obviously, case cling slows it, but I'm still mystified by the results of w30wcf's nice test. Someday, if I find one, I'll have to section a .44-40 case and make further back of the envelope calculations.
Is it me or did you actually contradict your self slightly there?

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

Not that I can see. I was only pointing out there's plenty of pressure to blow the case back in the time available--but only if you assume it doesn't cling. If you assume cling is enough to contain the pressure, time doesn't matter. Perhaps I didn't understand your earlier comment?
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Nath »

How I see it.....no maths involved at all.
The same pressure propelling the bullet, once swaged to the bore has little resistance hence it's fast accelleration, is also not just simply forcing the case in the opposite way but also radially. The radial effect of the pressure forces the case to the chamber wall.
Any rear ward travel is severly restricted as the surface area is greater on the chamber walls than just the rear end of the case. This happens at peak pressure!
When the pressure drops to a low pressure the case lets go at an undetermind point, a variable point, and then all be it at a lower amount of pressure the case MAY bear on the bolt or mechanism.
Time...the time scale is so short that the pressure struggles to gather any momentum by it's self.
I remember seeing a simple experiment. A 500hp car could not pull off with about 10 strong guys holding it on a rope! The car had developed no momentum to overcome.....
A cartridge case does not gain the momentum the bullet does because it is breaked!
By the time there would be enough time the driving force-pressure has drop to atmospheric again.
The peining affect to the brass head would by dramatic if peak pressures allowed the case to hammer the bolt face all the time. Try it.... put some drill rod in a case and hammer it to a vice or something. See how soon it mashes. Do you think a hammer can achieve greater pressures than the charge?

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

Nath, I think I understand what you're trying to say. Unfortunately, maths is the only way to see if the argument has merit, and I don't have enough measurements of a .44-40 case to start.

At what pressure the case will blow out and begin to hug the chamber can be computed. It's the simple "hoop stress" in the case walls compared to the yield stress of cartridge brass. It's the same pressure at which the brass will relax as the pressure drops.

As for the cling, it's not just a matter of the surface area of the contact of the case walls to the chamber. The case head is being shoved back by the pressure, and the case cling is holding it forward. The brass case wall that's holding it forward isn't very thick, yet it must resist gas pressure working over a larger cross section than it is. This acts as a pressure multiplier. If that multiple exceeds the yield stress of the brass, the case wall will yield, and the case head will move back to the breech while the rest of the case clings to the chamber.

There is much to consider in this problem. The answer is not trivial, and w30wcf's nifty experiment gives one reason to ponder the problem further.
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.44-40 bolt thrust Pic added

Post by w30wcf »

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I had added a piece of scotch tape over the case head to keep the clay from possible sticking to the bolt face.

I would expect that as pressures would increase, the case head would eventually overcome the primer thrust and reseat the primer but this is specifically a test of low / standard SAMMI pressure for the .44-40......

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Nath »

KWK wrote:Nath, I think I understand what you're trying to say. Unfortunately, maths is the only way to see if the argument has merit, and I don't have enough measurements of a .44-40 case to start.

At what pressure the case will blow out and begin to hug the chamber can be computed. It's the simple "hoop stress" in the case walls compared to the yield stress of cartridge brass. It's the same pressure at which the brass will relax as the pressure drops.

As for the cling, it's not just a matter of the surface area of the contact of the case walls to the chamber. The case head is being shoved back by the pressure, and the case cling is holding it forward. The brass case wall that's holding it forward isn't very thick, yet it must resist gas pressure working over a larger cross section than it is. This acts as a pressure multiplier. If that multiple exceeds the yield stress of the brass, the case wall will yield, and the case head will move back to the breech while the rest of the case clings to the chamber.

There is much to consider in this problem. The answer is not trivial, and w30wcf's nifty experiment gives one reason to ponder the problem further.
Lets not forget how the brass gets thicker nearer the head...and for good reason!

Hornet brass stays pretty thin all the way down to the cart' head and hence the notorious ring apears demonstrating the head moving possibly rear ward or is it the brass flowing forward? No two cartridge types are the same and the results as far (as I am concered) are not a forgone conclusion mathmatically or theory.

I do not think it is acceptable to condem an action such as a toggle link based on theory and or mathmatically. Modern toggle links will of been tested. Ok so they eventually shoot loose. Big deal. A 22-250 will soon eat a barrel.....so is it useless then?

Anyway is was/is a good discussion.

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by williamranks »

Just curious. If you put a couple drops of oil on the brass does the thrust go up?
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Nath »

williamranks wrote:Just curious. If you put a couple drops of oil on the brass does the thrust go up?
Good question...all I know is our proof is two stage. First the barrel is proofed. Then the action is and that involes a greased cartridge! Our guns are or were stamped on the barrel and the action!

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

Nath wrote:Lets not forget how the brass gets thicker nearer the head...and for good reason!

Hornet brass stays pretty thin all the way down to the cart' head and hence the notorious ring apears demonstrating the head moving possibly rear ward or is it the brass flowing forward?...

I do not think it is acceptable to condem an action such as a toggle link...
As the brass wall gets thicker near the base, it's ability to expand and grip the chamber wall falls off as well. I do believe the bright ring which appears on brass is simply where the brass yielded to the thrust on the case head and pulled it away from the case walls clinging to the chamber.

And you won't find me condemning the toggle link actions! I've wished someone would make an 1873 with an aluminum alloy receiver and elevator; it would get the weight down at least a pound and make for a more nimble handling rifle--one plenty strong enough for a .38-40 or the like. Both Winchester and Uberti have made '66s in silver, which is no stronger. But I diverge...
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Nath »

KWK wrote:
Nath wrote:Lets not forget how the brass gets thicker nearer the head...and for good reason!

Hornet brass stays pretty thin all the way down to the cart' head and hence the notorious ring apears demonstrating the head moving possibly rear ward or is it the brass flowing forward?...

I do not think it is acceptable to condem an action such as a toggle link...
As the brass wall gets thicker near the base, it's ability to expand and grip the chamber
wall falls off as well. I do believe the bright ring which appears on brass is simply where the brass yielded to the thrust on the case head and pulled it away from the case walls clinging to the chamber.

And you won't find me condemning the toggle link actions! I've wished someone would make an 1873 with an aluminum alloy receiver and elevator; it would get the weight down at least a pound and make for a more nimble handling rifle--one plenty strong enough for a .38-40 or the like. Both Winchester and Uberti have made '66s in silver, which is no stronger. But I diverge...
I don't see any reason to assume that due to a thickening of the head area of a case it severly obstructs its gripping ability. I do see it aiding in a resistance to stretching!
The 44-40 case illustrated gripped the chamber well. Hornet cases grip well. We don't get cases stretching like Hornet does in 44-40!

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

Nath wrote:I don't see any reason to assume that due to a thickening of the head area of a case it severly obstructs its gripping ability.
The thicker the case wall, the lower the stress. The lower the stress, the lower the strain. The lower the strain, the less the case diameter increases. The less it increases in diameter, the less it grips the walls.

Look it this way: both the primer pocket and the flash hole have very thick side walls--so thick neither expands enough to contact and grip the chamber walls.
The 44-40 case illustrated gripped the chamber well. Hornet cases grip well. We don't get cases stretching like Hornet does in 44-40!
Try running .44-40 brass at Hornet pressures?
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Nath »

"The thicker the case wall, the lower the stress. The lower the stress, the lower the strain. The lower the strain, the less the case diameter increases. The less it increases in diameter, the less it grips the walls."

The above comment is an assumption that the case will not grip the chamber! Tells us please just how thick must the brass be to grip 100%, 50% and 0%?


"Look it this way: both the primer pocket and the flash hole have very thick side walls--so thick neither expands enough to contact and grip the chamber walls."

Hmmm yesss but just above the head where the brass is thicker than the case/throat there is very often clear evidence of expansion :roll:

I give up....what was it King Soloman said....everthing is vanity and a chasing of the wind!

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

Nath wrote:Tells us please just how thick must the brass be to grip 100%, 50% and 0%?
Let's see, at the minimum, one needs the OD of the case, the ID and OD of the chamber, knowledge of the friction coefficient between the case and the walls at high loadings, and the yield stress of a work hardened brass case. These vary from rifle to rifle and among case lots. About all I can get on the back of an envelope is an estimate of .04 inches thick to yield a .44-40 diameter case at 13 ksi, but it will snug up against a tight chamber before that, after which friction and the expansion of the chamber comes into play. A full, 3D stress analysis is required, and Varmint Al's is the only one I've come across, but it was for the .243 Win. That or an enterprising fellow with a file and some bits of clay--I still can't figure that one out.
King Soloman said....everthing is vanity and a chasing of the wind!
Solomon must have been borderline nihilist.
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Nath »

KWK wrote:
Nath wrote:Tells us please just how thick must the brass be to grip 100%, 50% and 0%?
Let's see, at the minimum, one needs the OD of the case, the ID and OD of the chamber, knowledge of the friction coefficient between the case and the walls at high loadings, and the yield stress of a work hardened brass case. These vary from rifle to rifle and among case lots. About all I can get on the back of an envelope is an estimate of .04 inches thick to yield a .44-40 diameter case at 13 ksi, but it will snug up against a tight chamber before that, after which friction and the expansion of the chamber comes into play. A full, 3D stress analysis is required, and Varmint Al's is the only one I've come across, but it was for the .243 Win. That or an enterprising fellow with a file and some bits of clay--I still can't figure that one out.
King Soloman said....everthing is vanity and a chasing of the wind!
Solomon must have been borderline nihilist.
I bow to your superior ability to jibba jabba all day long and get absolutly nowhere.
I'll just stick to quietly observing and drawing my own conclusions from now on whilst the college types gloat over your pen collections. Whilst they are gloating I'll most probably be up the backwoods where there ain't no jibba jabba!

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

jibba jabba jibba jabba jibba jabba jibba jabba jibba jabba :D
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Well, I'll have you know that I like the Jubba jab , whatever. :D

W30wcf's picture tells a thousand words. Forget the jibba jive stuff, there ain't no bolt thrust at low pressures.---6
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

Sixgun wrote:W30wcf's picture tells a thousand words. Forget the jibba jive stuff, there ain't no bolt thrust at low pressures.
Whoa!: That has not been established! w30wcf's test shows the case head hasn't reached the breech (beats me why it didn't). A little jibba-jabba with a calculator says the primer cup had around 450 lb of rearward gas pressure on it, and we haven't established the extent of primer cling... :twisted:
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

KWK,
For real, I have always been a hands-on guy and make deductions from physical observation. I passed Algebra 1 and failed miserably at 2. I just can't grasp advanced math.

When an individual can't figure something out, frustration builds and I really want this all put to rest because I'm on the verge of hack sawing some fine rifles to make my own observations. There are an amazing amount of safety features built into even the old guns so it looks like I'm going to have to grab an old unused 92 or 86 barrel, stick in a low pressure cartridge and smack it with a hammer and a nail. :D

The point is I am looking forward to your math skills to put this to rest.-----6
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

Sixgun wrote:I am looking forward to your math skills to put this to rest.
I don't want to disappoint you, but the math required demands sophisticated (expensive) engineering software. Really, it would be far cheaper for me to do this by experiment. I've been thinking my T/C Contender would be the best way I could look into this. I'd need to strain gauge the breech area in one spot and calibrate it with a deadweight. This most certainly isn't going to happen in winter weather.

In his guise as w44wcf at CAScity, w30wcf once posted a picture of a sectioned .44-40 case, and I can get wall thicknesses from this. This weekend I'll try to find some time to make very rough stress calculations on the brass and see if I can explain (jibba-jabba) to myself the results of w30wcf's test. I'll let you know here what I get. This won't answer the primer thrust problem, though.

I really wouldn't go hacking your nice rifles were I you. This problem just isn't worth that!
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

w30wcf wrote:
Wed Nov 06, 2013 9:14 pm
Ok, finally had a chance to test the .44-40 ....... a few days later than anticipated. Life gets in the way sometimes .......

Anyway, the test indicates that the case head did not make contact with the bolt.

I used 2 cases with thinned rims (front) allowing for .015" headspace.
I seated the primers to stand .012" proud of the base of the case then applied 2 small clay pads on either side of the primer to the same .012" thickness.

Cases were loaded with 6.5 / Trail Boss / 215 gr cast bullet. Pressure 13,000 CUP or thereabouts.

Result:
Primer protruding .010" . Clay pads the same. No evidence that the case head touched the bolt since the small clay pads were not distorted as they would have been if the case head touched the bolt face.

I will say that the cases used were not full length sized. Just neck sized as I do all my .44-40's with a special die.

I'll post a pic in the next day or so.

52B,
Good points. I understand what you are saying. In this case, as it turned out, the primer pressure of approx. 65#'s (.08" flash hole / 13,000 cup) was enough in combination with the cartridge lock in the chamber to keep the case head from contacting the bolt.

w30wcf
Sixguns, this is not the post I was talking about but it will do for now. I wanted to add here that John used 6.5gr of Trail Boss. As we all know IMR's website lists this load as producing 12,000 cup which is about 10,000 psi. My pressure tests with the PressureTrace II strain gauges system is as follows.

Test #12

6.4gr Trail Boss
200gr 200gr Hard Cast "Magma" (Laser Cast type) sized .429 shot through a .429 barrel
10 shot test
Avg. 7,224 psi.

Test #19

9.4gr of Trail Boss
same components
15,182 psi

I would like to test known 14,000 psi loads with John's procedure
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by M. M. Wright »

This is very interesting but if you have read P. O. Ackley, as Jim T interjects, you already know that there is no such thing as bolt thrust. I am an old retired professor and SME member. I can do all those calculations that KWK insists on using but I know that Nath is right and KWK is wrong. The experiment comes out just as I would have expected. But then I read P. O. about 50 years ago. Of course if someone oils your case or you forget to wipe it, different results. But then that's the experiment that KWK's calculations apply to.
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by COSteve »

I only spent 41+ years in Aerospace so what do I know but if there's no bolt thrust, there's no recoil either. :roll: As the 'equal and opposite' forces to accelerating the bullet out the muzzle are exerted on the receiver and action, of which the bolt plays a central part, it seems to this old guy that call it what you want but there's a big force on the bolt when the round fires. :lol:

I'm not sayin that this is an absolute, exact measure of each caliber's bolt thrust in a 1873 Winchester, but rather it's a comparative estimate using the same formula for each caliber. I made it up some years ago to quantify the relative bolt thrusts in the '73's original calibers vs that produced by the newer pistol calibers. I wanted to see a comparison of the forces exerted on the bolt and therefor, the toggle link locking action, in the original 1873's action design as it's used in the current '60, '66 and '73 clone rifle designs.

My purpose in making up the chart was to evaluate the modern pistol calibers loaded to SAAMI spec levels and what bolt thrust those produced as compared to those produced by the 4 calibers the weapon was originally designed for. The results show what I expected; that there are modern pistol calibers that far exceed the thrust anticipated by the original design.

What that means to you is up to you. To me, it means that continuous, prolonged use of those high thrust calibers will eventually be detrimental to the firearm and eventually could cause it to fail.

Notice that even my crude calculations predict that even the lowly .22 produces nearly 900lbs of bolt thrust. Further, the numbers show why I've limited my .45 Colt loads to standard levels (14,000psi max) in both my '66 and '73 Ubertis as these levels are at the maximum produced by the original calibers they were chambered in. They also show why I choose not to own one chambered in .357mag or .44 Mag. I find the chart useful and informative even if 'bolt thrust' doesn't exist. :D

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Nath »

COSteve wrote:
Sat Oct 03, 2020 11:49 am
I only spent 41+ years in Aerospace so what do I know but if there's no bolt thrust, there's no recoil either. :roll: As the 'equal and opposite' forces to accelerating the bullet out the muzzle are exerted on the receiver and action, of which the bolt plays a central part, it seems to this old guy that call it what you want but there's a big force on the bolt when the round fires. :lol:

I'm not sayin that this is an absolute, exact measure of each caliber's bolt thrust in a 1873 Winchester, but rather it's a comparative estimate using the same formula for each caliber. I made it up some years ago to quantify the relative bolt thrusts in the '73's original calibers vs that produced by the newer pistol calibers. I wanted to see a comparison of the forces exerted on the bolt and therefor, the toggle link locking action, in the original 1873's action design as it's used in the current '60, '66 and '73 clone rifle designs.

My purpose in making up the chart was to evaluate the modern pistol calibers loaded to SAAMI spec levels and what bolt thrust those produced as compared to those produced by the 4 calibers the weapon was originally designed for. The results show what I expected; that there are modern pistol calibers that far exceed the thrust anticipated by the original design.

What that means to you is up to you. To me, it means that continuous, prolonged use of those high thrust calibers will eventually be detrimental to the firearm and eventually could cause it to fail.

Notice that even my crude calculations predict that even the lowly .22 produces nearly 900lbs of bolt thrust. Further, the numbers show why I've limited my .45 Colt loads to standard levels (14,000psi max) in both my '66 and '73 Ubertis as these levels are at the maximum produced by the original calibers they were chambered in. They also show why I choose not to own one chambered in .357mag or .44 Mag. I find the chart useful and informative even if 'bolt thrust' doesn't exist. :D

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The recoil forces are transmitted via the case.....that is gripping the chamber wall via higher pressure. Recoil is not generated by the case pushing on the bolt or other locking method. If it was one would have heck of a job working the action on an automatic action!

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by COSteve »

If there's no force on the bolt, why do the pins and holes in the '73's toggle system 'oval' over time firing heavy loads? Why are there smears on the bolt face of hot loads in a semi-auto? Ask Steve Young how many rifles and carbines he's had to repair due to bolt thrust.
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Sure there's bolt thrust...it just takes a certain pressure level to happen......case design and lubricant are major factors. Straight wall cases like the ones Jack Kort worked with shows there's virtually no thrust with the loads that the 44 that are normal in pressure.

Working with many antique guns over the years that had excessive headspace shows that....with light or normal loads the primer will back out to touch the bolt face showing no bolt thrust......as pressure rises the case head will flow back to push the primer back in and sometimes stretching the case depending on the level of pressure.

I'm just not smart enough to figure it all out so I just follow the standard safety rules.

Back in the day when I was around 20 or so I'd buy an 1873 and shoot the books listed powder weights and when opening the lever only the case head would come out....when I used black it never happened....what do you know when your a kid? For me, not much. Live, read, destroy, and learn----006
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Nath »

COSteve wrote:
Sun Oct 04, 2020 4:47 am
If there's no force on the bolt, why do the pins and holes in the '73's toggle system 'oval' over time firing heavy loads? Why are there smears on the bolt face of hot loads in a semi-auto? Ask Steve Young how many rifles and carbines he's had to repair due to bolt thrust.
Any force applied to the bolt is from lowered pressure. Or residual pressure. Once the pressure drops enough it no longer holds the brass against the chamber and for a very short time then moves the case against the bolt. Exactly the principle an automatic 22 works on.
If anything low power cowboy loads will have more opportunity to not grip the chamber and thus push against the bolt.
Another simple explanation for links loosening is the fact that some thrust or percussion does in deed exist but! It is not peak pressure and it is not related to high pressure rated cartridges
Remember, if cartridges did not grip the chamber at peak pressure there is no way we could have automatic firearms!
Remember, the primary roll of a locking mechanism or bolt or other is to support the cartridge head, period.
The worse the headspace the worse the percussion to the bolt. Little headspace, little percussion from the case head. Nothing to do with peak operating pressure.

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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Nath wrote:
Sun Oct 04, 2020 3:27 pm
Any force applied to the bolt is from lowered pressure. Or residual pressure. Once the pressure drops enough it no longer holds the brass against the chamber and for a very short time then moves the case against the bolt. Exactly the principle an automatic 22 works on.
If anything low power cowboy loads will have more opportunity to not grip the chamber and thus push against the bolt.
Another simple explanation for links loosening is the fact that some thrust or percussion does in deed exist but! It is not peak pressure and it is not related to high pressure rated cartridges
Remember, if cartridges did not grip the chamber at peak pressure there is no way we could have automatic firearms!
Remember, the primary roll of a locking mechanism or bolt or other is to support the cartridge head, period.
The worse the headspace the worse the percussion to the bolt. Little headspace, little percussion from the case head. Nothing to do with peak operating pressure.N.
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Old Savage »

Didn't Ackley demonstrate that there is almost no bolt thrust with his cases? Thus it would seem bolt thrust must be measured with different loads and cases and that no calculations will suffice without real world measurements.
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Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

COSteve wrote:
Sun Oct 04, 2020 4:47 am
If there's no force on the bolt, why do the pins and holes in the '73's toggle system 'oval' over time firing heavy loads? Why are there smears on the bolt face of hot loads in a semi-auto? Ask Steve Young how many rifles and carbines he's had to repair due to bolt thrust.
Because those are higher pressures, not low pressures. Because shooters lie about why their guns are broke, because they are stupid or got busted doing something they shouldn't.

Just because folks fail to wipe oil, clean cases, fail to check loads, doesn't mean low pressure loads come in contact with the bolt. Stop trying to re-direct the facts.
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