SAAMI Standardizes Hornady's 5.56 Commercial at 62,000 psi Maximum

SAAMI announced on October 12 from Shelton, Conn., that it accepted the 5.56 Commercial, a rifle cartridge introduced by Hornady Manufacturing, for standardization. The Sporting Arms and Ammunition Manufacturers’ Institute writes standards for the safety, reliability and interchangeability of firearms, ammunition and components.

The cartridge, abbreviated 5.56 COMM, pairs a 55-grain bullet at 3,400 fps with a Maximum Average Pressure of 62,000 psi. Crusher pressure limits are not established.

The drawings define the chamber and the test barrel used to measure velocity and pressure.

The safety question comes first for anyone with rifles already in use. SAAMI says its guidance is unchanged that only 223 Remington ammunition goes into a firearm chambered and roll marked only 223 Remington. Any 5.56 ammunition, including all military variants and ammunition made to this standard, raises pressure in a 223 Remington chamber and is considered an unsafe combination.

The standard does not settle how 5.56 COMM relates to 5.56 NATO. SAAMI says conforming to it does not imply conforming to any military or NATO specification. Because no publicly available standards exist for 5.56 x 45, including variants such as 5.56 NATO, SAAMI says blanket compatibility statements between those products and 5.56 COMM are impossible. For ammunition made to this standard in a firearm with a different roll mark, or the reverse, SAAMI tells owners to contact the firearm or ammunition maker.

Adoption is voluntary. Firearm makers do not have to mark guns 5.56 COMM, and ammunition makers do not have to use a 5.56 COMM headstamp, though SAAMI calls either marking acceptable practice. The announcement names Hornady as the introducer and lists no other maker that has adopted the cartridge.

SAAMI gives its reason in general terms. Standardizing cartridge and chamber designs, along with pressure standards, is key to its objective of safety and interchangeability across ammunition, firearms and suppressors. The package calls the specification a publicly available consensus standard for commercial practice, using the procedures and equipment in the American National Standard SAAMI Z299.4. SAAMI says Z299.4 is a free download from its website.

The introduction package is dated June 22, 2026, Rev. 0, and its chamber and test barrel drawings carry a June 9, 2026 issue date. SAAMI’s announcement page is dated October 12, 2026, and says the specification will be revised only through SAAMI’s defined consensus-based standards development and maintenance processes.