PPRuNe Forums - View Single Post - Russia claims their new future body armour will stop a .50 cal
Old 10th Feb 2021, 14:51
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rigpiggy
 
Join Date: Apr 2005
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Originally Posted by 911slf
It always was the same. It's the kinetic energy that kills you.

Imagine a ten pound gun firing a one ounce bullet at 1600 feet per second. It will recoil at ten feet per second. Momentum is 10*10 = 100 foot pounds. That's also true for the bullet 1/16 *1600 = 100 foot pounds.

Kinetic energy of gun is 1/2mv^2 (5*10^2) = 5*100 = 500 foot pounds.

Kinetic energy of bullet is also 1/2mv^2 (1/32 *1600^2) = 1/32 * 2560000 = 80,000 foot pounds. It's 160 times as much.

I don't know the actual values, this is illustrative. The recoil will also include that from the high velocity gas propelling the bullet, but I believe recoil suppression devices vent much of the gas backward - at the cost of making the gun even louder. I have never fired anything bigger than a 12 bore shotgun, and that is loud enough for me!

1 pound =7000 gr ergo 1oz is 437.5 gr Easy ke formula is (V*V)*min grains/450240) so your above 1oz shotgun slug at 1600 fps is about 2487 fpe And that is quite a stiff load not 80,000
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