[gbusmech]

I have seen something like that before, Movie gun loads. Blanks that will work in more than one caliber firearm. The ones I have most often encountered were head stamped 5 in 1 and would fit .38-40, .44-40 and .45 Colt hand guns plus the .38-40 and .44-40 carbines.

 

[gbusmech]

Don't blanks usually have an enlarged flash hole? That would be something to check.

I have a few kinds around here somewhere that I picked up from movie sets but I cannot remember even looking at the flash hole or even if I even punched out the primers. I'll dig some out and look and post what I find.

 

[gbusmech]

There is a wildcat cartridge call a 357/30 or 300 MAX Cat.

Doesn't that start with a .357 Maximum case?