This was in several years back copy of American Rifleman. I copied it verbatum as it has good things to print and file away for future reference. Sarge
Shooting Formulas
Bullet energy: E = (BW x V 2) divided by 450,400
Bullet energy is probably one of the most useful formulas for hunters. Adequate energy is one of the factors that assure quick clean kills on game. The only numbers necessary are the bullet weight in grains (BW) and the velocity in feet per second (V) Square the velocity then multiply the result by the bullet weight. Divide the entire product by the constant 450,400 and you have the bullet energy in foot-pounds at the velocity chosen. Remember if you want to know the bullet energy at a certain range then you must know how fast your bullet is going at that range
Sectional Density: SD = BW divided by BD 2
Sectional density is a useful number. The higher the SD number the deeper the bullet tends to penetrate; and also the higher the SD the less velocity the bullet loses during it's flight. As a numerical, the SD is the weight of the bullet in proportion to it's cross sectional area. Bullets being of varying diameters on it's length, the cross section area varies too, so for simplicity we divide the bullet weight in pounds (BW) by the diameter in inches squared (BD) There is 7,000 grains in a pound, so to convert to pounds, multiply the bullet weight in grains by .00014 or if it is easier for you, divide it by 7000.
Power Factor: PF = BW x MV
Many action handgun competitions require a minimum "power factor" (PF) or "lower floor" You should check with the specific sport in which you participate for the power minimum and the specific formula, but IDPA, IPSC and NRA Action pistol use a formula whereby you multiply the bullet weight in grains (BW) by the muzzle velocity in f.p.s. (MV) as measured on a chronograph at the shooting event.
I hope these formula's will help you. Print them out and have them tacked on the bullet board for handy reference.
Sarge
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