[Lonesome in Massachussets]

The only thing that counts in "stopping power" is transfer of momentum. The round has to have momentum = mass x velocity and it has to impart it to the target. A heavy fast round is generally better. Try a 105 Howitzer, if you can aim it with one hand. For hand guns, I think the M1911 (Army .45) if not the winner, is right up there and more than adequate for most work.

If a round passes through a target is does not impart all its momentum. If the round bounces off the target, counter-intuitively, it gets momentum from the target and actually transfers more momentum. If you had armor which caused bullets to bounce off, they would actually transfer more momentum than rounds that stuck to the armor.

In practice, you should chose a weapon for self defense that you are comfortable with. If the recoil or weight of a 0.45 is more than you can comfortably handle, you may be better off with a smaller weapon. Regardless, remember, keep shooting. "Why'd you shoot him 44 times?" , "Ran out of ammunition." One shot from a 0.38 is about as likely to infuriate as drive off an assailant. And shoot to kill. The sternum is a good target, even if you miss you might hit something.

[xm177e2]

If the round bounces off the target, counter-intuitively, it gets momentum from the target and actually transfers more momentum. If you had armor which caused bullets to bounce off, they would actually transfer more momentum than rounds that stuck to the armor.

Yes, but the momentum of a bullet is not all that much. The momentum of the bullet as it hits its target is less (because of air resistance) than the momentum when it left your gun. The recoil of your handgun is worse than the sheer momentum the victim feels. If the bullet bounces off, I suppose the momentum could be increased, but what matters is the

momentum/(surface area * time)

(I think--it's been a while since I did any physics)