Some great posts already made I wholeheartedly agree with.
Couple of points if I may:
One needs to consider environment and mode of dress.
.38spl is a lower pressure round, and for enclosed areas, such as vehicles, less deafening than .357.
158gr standard pressure was what .38spl guns were regulated to shoot POA/POI, shot placement is a huge key in round effectiveness.
FBI is a good load, and back in the day, we shot dirt, not for penetration, instead to see how reloaded bullets held up. Some bullets were factory, some made from wheel weights, etc.
Scientific Mud/Dirt Test and if one goes to Tom Given's site,
www.rangemaster.com, and read the latest newsletter, Mr. Givens shares what Mentors did when I was coming up.
Bones and Skin and load testing.
Skin is elastic, and bones do things to bullets.
In our day, SM/D Test, shooting dirt, we also put a rain slicker, or poncho over the box (skin) and added bones, chicken, ham, game cleaned - whatever.
Amazing how bullets recovered from plain dirt, and those with "skin and bones" replicated those removed from critters felled.
People and critters do not know, they are supposed to act a certain way with makes, models , calibers and bullets.
Recently, we took a 1929 Colt Detective special, and old Model 36 snub nose with UMC 158 gr LRN, standard pressure ammunition, that old "Widow Maker" load and put down a cow each.
One shot from each gun, and each cow went down.
This is not uncommon and has been done forever.
.38spl is a proven round, it will do its part, if the user does theirs.