The problem with ammo for the sub-optimal, non-duty calibers is that you have to choose between penetration and expansion. The rounds that expand a lot generally will fail in the penetration department, and the ones that penetrate generally don’t expand. I prioritize reaching the important parts and breaking them over pretty mushrooms. For me, that also includes barrier penetration, not just plain gel and clothed gel testing. I have shot a bunch of standard pressure .380 ammo against some stout barriers, and ALL of the hollowpoints and lead core FMJ have failed miserably against barriers that standard pressure 9mm and 40 S&W Speer Gold Dot hollowpoints will sail right through.
My locked breech .380s are loaded with Underwood standard pressure 68 grain XD rounds. That was the round that penetrates barriers but does not overpenetrate in the absence of barriers.
Barrier test 1
My 9mm P365 shooting 124 grain standard pressure Gold Dots against the same array resulted in the bullet sticking out of the back of jug 2.
Barrier Test 2
No barriers:
I shot this one other time and the round penetrated to the back of jug 4 and made a dent in jug 5. The wind was too crazy to publish that one. Also, a 124 grain standard pressure 9mm Gold Dot fired out of a Sig P365XL expanded a lot but stopped in jug 3.
The OP mentioned the plastic/copper powder rounds. Here is one:
Blazer FMJ:
I re-ran this test and got the same result.
I have some hollow point videos if someone wants to see a particular one that I have.
I should also point out that the P365-380 loaded with these Underwoods is a lot easier to shoot rapidly, with no loss of accuracy, than my 9mm version of P365. Also note that the .380 has open sights while the 9mm version has an RDS.
Again? 
