.45 ACP and Pressures

[NikatKimber]

Yes, the expanding gasses generate pressure, which is what pushes the bullet down the barrel. But no, I'm not really over complicating it. The "recoil" is the sum total of the pressure applied rearward to the gun for the entire time it is in the barrel. So for a powder that generates 29k psi for 75% of the time in the barrel, there will be more total recoil (and higher velocity) than for a powder that generates 32k psi for 25% of the time in the barrel.

Higher MAX pressure does NOT mean more total recoil. Higher AVERAGE recoil would.

 

[shortgrass]

From ignition to the time the projectile leaves the barrel the pressure is NOT constant!

 

[NikatKimber]

That's exactly what I'm saying.

A higher MAX pressure does NOT necessarily mean more recoil (or velocity). Higher AVERAGE pressure does.

 

[Rod Snell]

A (Very) Short Course in Internal Ballistics
http://www.frfrogspad.com/intballi.htm

A rigorous treatment of internal ballistics requires a knowledge of integral calculus. The integral of the pressure curve (the area under the curve) is the total WORK done on the bullet, and recoil is directly proportional to the WORK, not to the peak pressure. Matter of fact, the peak pressure does not directly determine much of anything except the max strain on the barrel.

For those that don't do calculus, Nikatkimber's explanation is close enough.

 

[NikatKimber]

I guess it is basic, in that it IS an "equal and opposite reaction" but it takes some good understanding of college level physics/math to predict the initial action in the first place.

A (Very) Short Course in Internal Ballistics
http://www.frfrogspad.com/intballi.htm

A rigorous treatment of internal ballistics requires a knowledge of integral calculus. The integral of the pressure curve (the area under the curve) is the total WORK done on the bullet, and recoil is directly proportional to the WORK, not to the peak pressure. Matter of fact, the peak pressure does not directly determine much of anything except the max strain on the barrel.

For those that don't do calculus, Nikatkimber's explanation is close enough.

 

[ldp4570]

"Oh bother" said Pooh, as he loaded another round!!

 

[aeropb]

"Oh bother" said Pooh, as he loaded another round!!

less calculus, more blowing **** up!

 

[Rod Snell]

Then quit asking questions about internal ballistcs and go shoot.....
It's a lot more fun and not nearly as complicated.
Front sight, squeeze.........

 

[technetium-99m]

Rod

Are there any references to compare medium and fast burning pistol powders being related to felt recoil (kind of an abstract term I guess).

Loaded to the same PF I much prefer faster powders for USPSA (as do most others shooting non compe'd guns). This seems to be true for 45/40/9/and 38 super (non compe'd gun). The sights track better and it "feels" as if there is less recoil (the gun may just be behaving differently though). Is there anything looking at pressure curves vs. slide speed (or some other variable) that may explain these differences. Or is it all in my head?

Thanks for the read!

 

[technetium-99m]

Then quit asking questions about internal ballistcs and go shoot.....
It's a lot more fun and not nearly as complicated.
Front sight, squeeze.........

Well I don't care about terminal ballistics for USPSA, as long as the popper falls over I'm cool. And There doesn't seem to be much to the external ballistics of my 40 cal loads. So this is all I'm left with.

Ha ha ha