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I use the same formula as A Johnston except I use the short form. For example:

185 gr
1100 mv

110 squared= 12100 divided by 4504=2.69

78 Posts
The formula for Kinetic Energy (KE) is

(1/2) x Mass x (Velocity squared)

Mass of the bullet is obtained from the grains of the bullet divided by 7000, conversion from grains to pounds, 7000 grains per pound, then you have to divide that number by 32.2. 32.2 ft/sec-squared is the acceleration factor from gravity, from our friend Sir Issac Netwon. The term for mass in the English system is "Slugs".

The 64.4 is from 32.2 x 2, if you write out the complete formula, you will see how this comes about.

Then you multiply this whole thing by velocity squared.

And you have KE. If you want to have some fun, and see why Hollywood is wrong about knock down power, look at the momentum calculation. Monmentum is: Mass x Velocity

Calculate mass as I show above for a bullet and for a human or animal weight and compare the velocities. If you do this the you will see the Hollywood view of someone being blown back from a gun shot is complete non sense.

Have Fun

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