SAAMI – pistol

SAAMI maximum chamber pressure for specific cartridges.

CartridgeCUPS PSI
380 Auto17,00021,500
9mm Luger33,00035,000
9mm Luger +P38,500
38 Special17,00017,000
38 Special +P20,00020,000
357 Magnum45,00035,000
40 S&W35,000
10mm Auto37,500
41 Mag40,00036,000
44 S&W14,00015,500
44 Magnum40,00036,000
45 Auto18,00021,000
45 Auto +P23,000
45 Colt
See Special
14,000 14,000
45 Colt +PNot DefinedNot Defined


SAAMI ( Sporting Arms and Ammunition Manufacturing Institute) is an organization that defines extensive definitions for cartridges of ammunition. It includes the cartridge physical dimensions as well as maximum chamber pressure. This ensures that ammunition manufactured as a specific caliber is safe for that type of firearms with assuming a firearm in a good functioning condition.

Copper Unit of Pressure (CUP) is a measurement used in the ammunition industry to determine the chamber pressure created by a cartridge load. Originally, a precisely formed copper slug was placed in a fixture over the chamber. When the cartridge was fired, the amount of crushing measured on the slug allowed engineers to determine the pressure.

These days, modern electronic transducers provide faster, more accurate measurements of chamber pressures in pounds per square inch (PSI). CUP and PSI are measured to different scales and are NOT interchangeable.

+P Ammunition — This ammunition is loaded to higher pressures than the original level of that caliber. It is typically used for defensive ammunition. It’s overall size and shape is identical to its parent cartridge, so care should be used to only use +P with firearms with sufficient strength to handle the additional pressure.