The SASS rules regarding revolver calibers are: - Must be centerfire cartridges of at least .32 caliber and no larger than .45 caliber or percussion calibers of at least .36 caliber and no larger than .45 caliber.   - Must be in a cartridge commonly available in revolvers. Examples include, but are not limited to, .32-20, .32 Magnum, .357 Magnum, .38 Special, .44 Magnum, .44- 40, and .45 Colt. (Includes some semi-auto pistol cartridges, e.g. 9mm, 10mm, and .45 ACP) SHB p.37