Bullet diameter, power factor, and pressure

drmitchgibson

The white Morgan Freeman
I got some 125gr .38 cal projectiles in a couple sample packs from a goody bag at the High Desert classic. Montana Gold. I grabbed them because the other MG 9mmish projectiles were in retarded weights like 121gr. .38 cal is .357. So I gave it a shot loading them as if they were 9mm.

Loaded all 20 at the same charge and dimensions as my 124gr Blue Bullets load. The MGs fed and fired. The speed was identical to the 124gr Blues, so the power factor was virtually identical. But the extra thou of diameter created more case pressure. Primers flattened, and the gun had trouble extracting.

It was interesting.
 

Scott Hearn

Well-Known Member
Mitch Gibson said:
I got some 125gr .38 cal projectiles in a couple sample packs from a goody bag at the High Desert classic. Montana Gold. I grabbed them because the other MG 9mmish projectiles were in retarded weights like 121gr. .38 cal is .357. So I gave it a shot loading them as if they were 9mm.

Loaded all 20 at the same charge and dimensions as my 124gr Blue Bullets load. The MGs fed and fired. The speed was identical to the 124gr Blues, so the power factor was virtually identical. But the extra thou of diameter created more case pressure. Primers flattened, and the gun had trouble extracting.

It was interesting.
Just back off the charge a couple of tenths. The diameter itself won't hurt a thing. Check out this (#eight) : http://www.schuemann.com/Portals/0/Documentation/Schuemann%20Instruction%20manual.pdf
 

noylj

Member
Never had any pressure signs from going from 0.355 to 0.357" jacketed.
Main thing to remember is that the bore/groove for barrels is the same for 9x19, .38 Spl, and .357 Mag.
 

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