Some years ago, the new York city police dept. did a survey of 5,000 shootings. They came to the conclusion that it really did not matter what the victim was shot with, as much as shot placement.
I did some shooting on wet phone books, and found that in most 2 inch barrel .38 revolvers there was not enough velocity to open up the hollow points in over the half the recovered bullets. On top of that, a 150 grain SWC out of an old Colt detective special, did not penitrate as deep as a .22 high speed hollow point bulk box Federal out of a 4 inch model 63 kit gun. The .22 hollow point did expand into a nice misshapen piece of lead.
Its all gonna depend on what you hit. Take out a liver, heart, brain, your target goes down. Get a hit in one of those empty cavities the human body is filled with, you're gonna have to keep shooting.
Use whatever gun and load your comfortable with, and then practice till you know that weapon combo better than you know the back of your own hand. Do your part, and you'll be fine. A mild target load out of a snubby .38 should work if it gets in the right place.