My Sierra manul suggest using there .357 bullets in the 38 Super.Any one out there had any luck with this size bullet?

Also need powder sugestions.

SOME aftermarket barrels are cut for .357diameter barrels.

Most factory and aftermarket barrels are cut for .355 (9mm) bullets.

the typical shape of most .357 bullets are not conducive to feeding correctly in a semi-auto.

AllanD

The manul didnt elaberate on different barrel diameters as a matter of fact about all thats mentioned is that they found that the 38 super was more accurate when the .357's are used.Did Sierra at sometime not make .355 ???

It's possible they did their load development on a early spec chamber.

The original colts were SUPPOSED to headspace with a narrow piece of the semi rimmed cartridge's rim against a step in the inderside of the barrel hood extension.

In practice the 38super actually headspaced with the cartridge extractor groove against the extractor.

LATER chambers are cut shorter to headspace the cartridge against the case mouth

It's likely that the fatter bullet (which will swage down on firing) will give more positive location of the cartridge in the chamber and thus more accuracy.

I still have the original 1969 barrel for my 38-super, but I long ago replaced it with a Colt NM barrel and collet type bushing which is cut to headspace on the case mouth.
I load only .355 bullets for the 38super.

AllanD