I would never after 40+ years of carrying a defensive gun, carry a 380 in order to save 1/2 inch of space.... You just cannot compare a 380 with a 9mm. It is apples and oranges. Like a 357 and a 38.
I wanted something that fit in my front pocket and was capable of 12+ inches of penetration through 4 layers of heavy denim.
All of the testing that I could find at the time had .380 hollow point stopping at 10" penetration and the FMJ, even truncated flat nosed penetrating 17-18 inches and even zipping out the back of 19" blocks.
There didn't seem to be a way to get the round to penetrate between 12 to 15 inches.
.40 S&W and .45 ACP couldn't be made small enough or light enough to fit into a pocket.
The Rohrbaugh R9 could fire the 9mm cartridge out of a ~3" barrel and deliver 14 - 15" of penetration through 4-layer denim and still expand to around .60+ caliber.
So I bought one
My problem with the 380 AUTO at the time was that most of the gel tests I'd seen showed the hollow points topping out at 10" penetration (when they expanded) and the FMJ, even truncated flat nosed penetrating 17-18 inches and even zipping out the back of 19" blocks.
There didn't seem to be a way to get the round to penetrate between 12 to 15 inches.
That may be changing with new bullet designs.
In the late 80s and early 90s the FBI was driving bullet design and development for the 9mm and 40 S&W, and we saw tremendous improvements in bullet designs and terminal performance. IMO though, the ammo manufacturers didn't put nearly as much research or development effort in the 380 ACP. They did however, slap their name brands on the 380 cartridges, which gave the impression that 380 rounds like PDX and Golden Saber were going to perform as well as their big caliber cousins. What we saw though is that many of these name-brand cartridges don't do any better than any of the other 380 loadings out there, and don't do that well in general. Many of the hollow points had a high failure rate and when they failed to expand, would penetrate 20+ inches, and when the hollow points did expand they usually stopped short of 10"
Now we've seen a boom in the 380 ACP pocket pistol market with many owners who are intelligent shooters with good knowledge of terminal ballistics now looking for 380 cartridges that perform well out of the 3" barrels.
I think that is creating a market for someone to create bullet designs and loadings that penetrate 4 layers of denim and penetrate to around 13" of gel with some (controlled) expansion, out of 3" barrels.
I think we will see improved 380 ACP performance in the future. We've seen Precision One's loading of the Hornady XTP yield good results in testing. We're already seeing interesting designs like the Lehigh Xtreme Penetrator.
Like the 9mm versus .40 S&W debate of the past - the question may not be .380 ACP as a gun, the answer may be the
cartridges developed for the gun.