Muzzle energy is the kinetic energy of a bullet as it is expelled from the muzzle of a firearm. It is often used as a rough indication of the destructive potential of a given firearm or load. The heavier the bullet and the faster it moves, the higher its muzzle energy and the more damage it will do.
The general formula for the kinetic energy is:
When using a system of units that is not self-consistent, or if the weight of the bullet is used rather than the mass, a conversion factor must be added. For example, to get muzzle energy E in foot-pound force, where
the formula is
Most sporting arms publications within the United States report muzzle energies in foot-pound force, and, when publishing kinetic energy tables for small arms ammunition, use a dimensional constant of 32.163 lbm • ft / lbf • s² rather than the standard acceleration of gravity of 32.1739 ft / s².
The bullet energy, remaining energy, down range energy and impact energy of a projectile may also be calculated using the above equations.
|(ft • lbf)||(J)|
|pistol (semi-auto)||9 mm||350||540|
Average muzzle energies E in foot-pounds for common pistol cartridges:
|9 mm Luger||350|
Edward F. Obert, Thermodynamics, McGraw-Hill Book Co., 1948.
Mc Graw-Hill encyclopedia of Science and Technology, volume ebe-eye and ice-lev, 9th Edition, Mc Graw-Hill, 2002.