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JGarcia · 06-30-2004, 11:49

How do you determine the number of Joules a bullet develops on impact?

For example, say you have a 123 grain bullet, travelling at 2198 FPS, or 670 MPS. A joule is equal to the kinetic energy of a two-kilgram mass moving at the speed of one meter per second.

a 123 grain bullet is .0079 kg, a 62 grain bullet is .004kg, when multiplied by the muzzle velocities of 670MPS, and 850 MPS respectively, I think that the amount of joules developed by each round should be 5.29 joules and 3.4 joules.

If I did this correctly, this should mean that the 7.62x39 has kinetic energy at the muzzle than the 5.56 NATO. This has absolutely nothing to do with accuracy, simply just kicking around the amount of energy delivered to a target.

I suppose the way to determine the amount of joules delivered to a target at a certain range, one must know the speed of the projectile at that range.

Also, what is the correct formula to determine PSI for the round striking a certain spot at a certain range, given the joules? Can you simply convert from joules to PSI? I think this would be handy to determine exactly how much barrier material one would need.

Had some free time. Did I do this correctly?

06-30-2004, 11:49	#1
JGarcia Guerrilla Join Date: Feb 2004 Location: San Miguel, CA Posts: 407	Joule How do you determine the number of Joules a bullet develops on impact? For example, say you have a 123 grain bullet, travelling at 2198 FPS, or 670 MPS. A joule is equal to the kinetic energy of a two-kilgram mass moving at the speed of one meter per second. a 123 grain bullet is .0079 kg, a 62 grain bullet is .004kg, when multiplied by the muzzle velocities of 670MPS, and 850 MPS respectively, I think that the amount of joules developed by each round should be 5.29 joules and 3.4 joules. If I did this correctly, this should mean that the 7.62x39 has kinetic energy at the muzzle than the 5.56 NATO. This has absolutely nothing to do with accuracy, simply just kicking around the amount of energy delivered to a target. I suppose the way to determine the amount of joules delivered to a target at a certain range, one must know the speed of the projectile at that range. Also, what is the correct formula to determine PSI for the round striking a certain spot at a certain range, given the joules? Can you simply convert from joules to PSI? I think this would be handy to determine exactly how much barrier material one would need. Had some free time. Did I do this correctly? __________________ National Guard Marksmanship Training Center Last edited by JGarcia; 06-30-2004 at 11:56.
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