For decades, there has been an odd gap in the standards world. There has never been a publicly available standard for 5.56x45, even though millions of rifles are roll-marked for it. SAAMI has now filled that gap from the commercial side with 5.56 Commercial, abbreviated 5.56 COMM, introduced by Hornady.
The numbers are a 55-grain bullet at 3,400 fps and a Maximum Average Pressure of 62,000 psi. For comparison, SAAMI rates .223 Remington at 55,000 psi, which is why the warning about mixing the two still stands. The introduction package is dated June 22, 2026, and the chamber drawings are dated June 9, 2026.
Here is the announcement from SAAMI:
“The Sporting Arms and Ammunition Manufacturers' Institute®,Inc., (SAAMI®) has announced the acceptance of a new rifle cartridge for SAAMI standardization. SAAMI is the organization at the forefront of promoting firearm safety by creating standards that ensure safety, reliability and interchangeability of firearms, ammunition and components.
Click on the cartridge name to open the introduction package.
5.56 COMMERCIAL – The 5.56 COMMERCIAL (abbreviated name 5.56 COMM) was introduced by Hornady Manufacturing Company with a 55-grain bullet traveling at a velocity of 3,400 fps and a Maximum Average Pressure of 62,000 psi.
The 5.56 Commercial cartridge and chamber defined here provide a publicly available consensus standard describing a chamber and ammunition system for commercial practice using the procedures and equipment detailed in the American National Standard SAAMI Z299.4[1].
Conformance to this specification does not imply or ensure conformance with any military or NATO specification. The absence of publicly available standards for "5.56 X 45", including variants such as "5.56 NATO", makes blanket compatibility statements of those products to products manufactured to this new standard impossible.
The 5.56 Commercial specification is a commercial SAAMI standard and will be revised only through the defined SAAMI consensus-based standards development and maintenance processes.
As a voluntary standard, the existence of this specification does not require firearm manufacturers to mark firearms as 5.56 Commercial (or 5.56 COMM), nor does it require ammunition manufacturers to adopt a 5.56 Commercial (or 5.56 COMM) headstamp, although the use of this designation as a roll mark or headstamp is acceptable practice.
For specific questions on the compatibility of ammunition made to this specification in firearms carrying a roll mark other than 5.56 Commercial (or 5.56 COMM), or vice versa, contact the manufacturer of your firearm or ammunition for further information.
Existing guidance that ONLY 223 Remington ammunition is to be used in a firearm chambered and roll marked as only "223 Remington" remains unchanged. The use of any 5.56 ammunition, including all military variants as well as ammunition produced to this standard in a 223 Remington chamber creates increased pressure and is considered an unsafe combination.
For further information on this new cartridge please click here.
The standardization of cartridge and chamber designs, along with pressure standards, is key in the achievement of SAAMI's principal objectives of ensuring the safety and interchangeability of ammunition, firearms and suppressors. These standards provide manufacturers with appropriate guidelines to ensure proper and safe operation and interaction of their products for shooting sports enthusiasts.
[1] This standard is available as a free download from the SAAMI website here.
About SAAMI: The Sporting Arms and Ammunition Manufacturers' Institute, founded in 1926 at the request of the federal government, is dedicated to creating and promulgating technical, performance and safety standards for firearms, ammunition, suppressors, and components, and is committed to being the preeminent global resource for the safe and responsible design, manufacture, transportation, storage and use of these products.”
The compatibility language is the part worth reading twice. Conformance to the 5.56 Commercial specification does not imply conformance with any military or NATO specification, and because no public standard exists for 5.56 X 45, blanket compatibility statements between those products and products built to the new standard are impossible. For specific questions, SAAMI points buyers back to their firearm or ammunition manufacturer.
The .223 Remington rule has not changed. Only 223 Remington ammunition belongs in a firearm chambered and roll marked as only 223 Remington. Any 5.56 ammunition in that chamber, military variants and ammunition made to this new standard alike, creates increased pressure and is considered an unsafe combination.
Nothing here forces anyone's hand. As a voluntary standard, it does not require firearm makers to mark firearms as 5.56 Commercial, and it does not require ammunition makers to adopt a 5.56 COMM headstamp, though using the designation is acceptable practice. The specification will be revised only through SAAMI's consensus-based process.
5.56 Commercial (5.56 COMM) key specifications
Does a published commercial 5.56 standard change anything for you, or is it mainly a manufacturing matter?
For more on the subject, read this article: 5.56 vs .223: What's the Actual Difference?
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