Just got a chance to shoot my new M1A1 Thompson on a full gas recharge. I slammed a cambells soup can at 25 feet dead center on semi auto mode and the bb went in and out of the can! Thats the heavy tin cans not the thin aluminum soda cans. Pretty impressed with the punch. If can do that to a can it can do some serious damage to someones head. I bet that would also penetrate someones bare flesh an inch or more.