I was taught long ago to not worry about overpenetration too much. Be more worried about the rounds you launch that miss. That said, I can tell you without a doubt, that the .38 LHP gives great penetration, good holes, great expansion under most circumstances, and usually stays within the target. My last deer took one dead broadside, through the shoulder muscles, and stopped just under the out-going hide. Deer ran about 30'ish yards and fell over dead. Great burglar performance. Though a burglar would have had, more than likely, more than one sent his way. And this was with the 4" velocity and a Buffalo Bore load, 964 fps(Standard Pressure, NOT Plus P). Not too many animals or criminals do well with one or multiple half-inch plus holes through vital organs. Compared to a .357 Mag Rem SJHP 158 gr with the same barrel length, the effect on the animal was identical, regarding Whitetailed Deer. I would never hesitate to EVER carry this .38 load for normal self-defense situations.