:bull: Momentum = Mass X Velocity. The rifle, due to its mass, will recoil much slower than the velocity at which the projectile leaves the barrel. Momentum for the ball and the rifle will be equal, but the force will be distributed over a much greater time for the rifle than that of the ball. Pull out your highschool physics book and reread the chapter on kinematics.
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No sir, go a bit beyond your high school physics book and you will find that the rocket effect of the escaping powder gas after the projectile has exited the bore adds considerably to the recoil while adding nothing to projectile velocity. Thus the recoil momentum is greater than projectile momentum right at the muzzle. Plus, since we seldom shoot game quite that close, the projectile is being slowed by air resistance so that by the time it reaches the game the projectile momentum is less than half the recoil momentum of the gun and at 100 yards with round balls may be less than one third.
In any case, if momentum is the basis for your favorite formula for killing power then your gun is more deadly at the rear than at the front.
However, when you look at kinetic energy you find the projectile has many, many times the recoil energy of the gun. I find those numbers more reasonable.
Jeff Cooper, writing for Guns & Ammo thirty years ago came up with a pet "stopping power" formula. A letter to the editor pointed out that by Cooper's formula a well pitched softball would have more stopping power than a .44 mag. Cooper replied "that just shows that anything can become ridiculous if carried to ridiculous extremes". Wrong Jeff, if a mathematical formula has validity it remains valid regardless of the size of the numbers one may plug into it. Pi r square works as well for a pin head or a planet because it is a valid equation. By carrying it to the extreme the flaws of Coopers formula became obvious. I think the fact that recoil momentum exceeds projectile momentum makes the flaw in those numbers obvious.
Like it or not, kinetic energy is the only valid measure of a projectile's ability to do work. That it is not a reliable measure of killing power I certainly do agree, because there is no such measure. Put even the very smallest bullet through the heart of an elephant and you'll very soon have a dead elephant. How do you quantify that?
People insist on applying John Taylor's knock out values in exactly the way Taylor repeatedly stressed they should NOT be applied. He stated it was NOT a measure of "killing power", not to be applied to high velocity rifles on thin skinned game and he admitted that, in his own experience, some calibers seemed to perform better than the numbers would indicate and some not as well. Now we see people even applying it as a measure of handgun stopping power. Taylor would be highly offended by that.
