Optimum Game Weight

Optimum Game Weight (OGW) is a formula developed by Edward A. Matunas to aid the hunter in selecting a cartride/load appropriate to the game being hunted.  I don't know where else this may have appeared, but it is in Lymans 47th Reloading Manual.  Included with the article are tables of game weights, OGW ratings at 0 to 400 yards for most factory loads, and OGW ratings for velocities to cover most common bullet weights.

We've all heard the arguments regarding kinetic energy versus momentum.  Many authors have attempted to come up with an objective method of determining the "Killing power" of cartridge loadings.  This is one that actually makes sense.  It differentiates light bullet energies and heavy bullet energies with a degree of rationale I've not found in other systems. It produces numbers that most experienced hunters will find intuitively correct, expressed in a form that is convenient for the hunter, optimum game weigt in pounds.  The weight calculated assumes that occassionally you will take a hard quartering shot.  If you push the envelope, the author suggests that you choose a load that will deliver a 25% heavier rating.  This alsobassumes that the bullet chosen is constructed appropriately for the game being hunted. 

The formula is V * V * V * B * B x 0.0000000000015 (that 1.5 to the -12 power) for hunting bullets.  Change the constant to -13 power for varmint bullets.  V is the impact velocity in feet per sec and B is the bullet weight in grains.  Kind of a pain to calculate manually but it is one of the columns I calculate in the Ballistics Calculator.  For your convenience I have copied the Game Weight Table that accompanies the article to a page for you.  Some of the average weights listed are far lighter than I would have guessed but they are purported to be based on "a great deal of research", so I won't argue.

Give it a try, I think you will be pleasantly surprised with how close to reality, as you know it, the numbers are.