Physics of Rifle Shooting Home Introduction Conservation of Momentum Conservation of Energy Bullet Drop Sighting in Bibliography Stopping Power: Conservation of Energy When hunting big game it is important to deliver enough energy to the target in order to ethically harvest the animal. You can easily calculate the kinetic energy of the projectile with the equation   KE = ½ Mv2 The mass and muzzle velocity of a bullet is often printed on the ammunition box, but can also be found on the manufacturer's website. Bullet mass is often given in grains ( 15.4 grains = 1 gram) and the velocity in feet per second (3.28fps = 1mps). For example, a common loading of a .308 Winchester cartridge uses a 165 grain (0.0107 kg) bullet and has a muzzle velocity of 2700 feet per second (823.2 m/s). The energy of the bullet from this cartridge would be around 3630 Joules. Bullet fired into sample of ballistic gelatin http://www.gelatininnovations.com/pages/ballistic.html