DocRocket
I've done extensive load workups/tests with heavier bullets in 380, and frankly, it's a waste of time and components unless you just want to tinker.
To get any velocity, you need to load at max or above-max powder charges. In my experience you can't get sufficient velocity with 115 gr or heavier JHP's to give reliable expansion, and if they do expand, penetration sucks. By reliable expansion, I mean the bullet actually expands as designed in at least 7 out of 10 rounds tested. Most people who reload 380 with bigger bullets never do the penetration/expansion tests. Or they fire one bullet into wet newsprint and it expands, so they figure they're GTG.
For defensive purposes, this is inadequate performance any way you slice it. You're better off working with a lighter JRN bullet which will at least give you some penetration.
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KevinGibson
Yeah, Doc has it right;
I have been doing overload testing on 6 different 380 pistols.
They are capable of sustained fire it three very different power levels based on:
1) Chamber wall thickness
2) feed ramp intrusion into case support
3) slide and barrel mass
4) recoil spring force
5) barrel length
Low power Between factory 380 and factory 9mm performance, if one could live with the recoil.
1) Kel-Tec P3AT 90 gr Gold Dot 1100 fps average
2) Ruger LCP
Medium power factory 9mm +P+ performance, if one could live with the recoil.
3) Jennings Bryco model 38
4) Kahr P380
High power factory 357mag performance, if one could live with the recoil.
5) Beretta 1934
6) Husqvarna 1907 [1187 fps 158 gr cast or XTP]
What makes the Kahr so good, is that there are trade offs between those pistols, but it may be the best for carry:
1) chamber wall thickness .063" [~ double the little guys]
2) case support .175" [perfect]
3) slide and barrel mass .0126 slugs [better than the little guys]
4) recoil spring force x travel = 0.8 foot pounds to return to battery [recoil energy also goes into hand movement + cocking + slide friction][ double the little guys]
5) barrel length is 2.53" [not so good, but more length will do nothing, as the pistol is recoil limited.]