CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.
I have analyzed and overload work up with hot loads on (6) 380s and divide them into 3 groups:
1) Poor case support, thin chamber wall, low mass slide, wimpy recoil spring.
Was ok for me for the equivalent Buffalo Bore +P 90 gr
Kel-tec P3AT
Ruger LCP
2) medium case support, chamber wall thickness, mass slide, and recoil springs.
Was good for me for double loads
Jennings Bryco
Kahr P380
3) Good case support to the case web, chamber wall is thick, high mass slide, stiff recoil spring
Was good for me for triple loads
Husqvarna Colt 1903
Beretta 1934
Notice how locked up vs blow back had nothing to do with it.
Notice how the wimps will fit in your shirt pocket for easy carry.