2 theoretical questions about ammo and projectiles

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RobSmith

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I was reading up on Dave L.'s school project the other day and a few things came to mind for the number crunchers on this board ...

1st : what would the maximum theoretical gas pressure that one could obtain from conventional powder, given unlimited case capacity, if there is such a thing ? (I would assume that the gases would turn back into solids if you get them at high enough pressure, high school chemistry is a little foggy but I think that's what happens :redface: )

2nd : what sort of maximum theoretical velocity could a conventional lead-core copper jacketed projectile before it either fell appart or melted and fell appart due to air friction ?

Just wondering if anyone ever tried to cruch those numbers ... :D
 
Never crunched any numbers, but I know that there have been pressures measured upwards of 130,000 CUP's (double charges, etc) and I know that you can get velocities in excess of 4000 FPS with some of the wildcat loads that exist.

Now, the 130,000 CUP chamber pressure will probably be enough to destroy your rifle, and rounds loaded to 4000 fps will burn out a barrel REALLY fast, so, back over to you.

NS
 
NavyShooter said:
Now, the 130,000 CUP chamber pressure will probably be enough to destroy your rifle, and rounds loaded to 4000 fps will burn out a barrel REALLY fast, so, back over to you.
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I fully realize that a barrel would need to be both insanely long and thick to survive such an experiment, probably would better be smoothbore too ... Just one of those "meaning of life" type of situations .. :evil:
 
It has been shown that smokeless powder does eventually develop a tendency to detonate in large quantities, so given unlimited case capacity I think you could generate pressure peaks MUCH higher than anything you see in small arms.
 
BattleRife said:
It has been shown that smokeless powder does eventually develop a tendency to detonate in large quantities, so given unlimited case capacity I think you could generate pressure peaks MUCH higher than anything you see in small arms.
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I'm trying to picture the kind of damage you would get from say, a howitzer that would have the barrel sleeved to .30 cal let's say .... Ouch!
 
RobSmith said:
I'm trying to picture the kind of damage you would get from say, a howitzer that would have the barrel sleeved to .30 cal let's say .... Ouch!
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lets say hello pipe bomb.
Very fun, but stand Far back.

Check out something called a light gas gun. It is quite interesting.
 
Practical experience tells me that:

1) it's all about the shape... with the right shape there is no limit... on the practical side consider Winchester Short Magnums - different shape of the case with less powder = same or more efficient rounds within reasonable chamber... not a rocket science, but some research was done.


2) Lead would melt at 2500 fps or 3000 fps... I forgot which one... but there are lots of variables here too.... How thick is the copper jacket? Bullet size? etc...

however, question for you... you have copper and steel, you have melting temperature for the copper.... go figure what the speed should be for the copper melt down when it moves against the steel... with the right textbook it's easy to solve...
 
Weatherby and Ackley conducted some experiments firing bullets to 5500 fps apparently, using light solid copper bullets and large charges of powder. The Weatherby experiments were with a .300 Weatherby and 55gr. bullets, results? Slightly elevated press.(could still open the bolt), lots of copper fouling, early throat erosion. Ackley actually blew guns up experimenting and talks a bit about it in his books "Handbook for Reloaders". careful with the reload info in this book as some of the loads are "HOT" or "WISHFULL THINKING"
 
guess_kto said:
however, question for you... you have copper and steel, you have melting temperature for the copper.... go figure what the speed should be for the copper melt down when it moves against the steel... with the right textbook it's easy to solve...
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Since I don't have any such texbooks here, I'll take a wild guess of around 5000 fps ? By then you probably end up with ionised air around the projectile and a nice green tracer as a result ... Esquif's article mentions 5300 fps as a theoretical gas speed limit so I guess that answers one of the questions.
 
guess_kto said:
2) Lead would melt at 2500 fps or 3000 fps... I forgot which one... but there are lots of variables here too.... How thick is the copper jacket? Bullet size? etc...

however, question for you... you have copper and steel, you have melting temperature for the copper.... go figure what the speed should be for the copper melt down when it moves against the steel... with the right textbook it's easy to solve...
Click to expand...

Pure copper melts at 1,985 degF and 1,085 degC; lead melts at 622 degF and 328 degC.
 
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