"The gun is a blow back with a 3 inch barrel"

Yup, that describes about 95% of all .380 pistols ever made!

Just use any faster powder, "Power Pistol" is about as slow as you should go for .380. Just use manual data, there is no reason to try to hot-rod any blow-back gun. If you have a chronograph then buy a few different factory loads and just try to duplicate velocity by experiment.

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Gunsmithing since 1961