.22 hollow points don't penetrate as deep when fired from a handgun because, while they don't properly expand, they'll get deformed, banged up, and yaw causing more drag. Round nose slips through tissue and pokes a .22 caliber hole in the target. Not the most ideal bullet, but a CNS hit will do it. The only .22 I've seen that does expand from a handgun is the Aguila Supermaximum and they penetrate about 10 inches. Not bad for a .22 pistol.