5.56 vs .223 and SAAMI's New 5.56 Commercial: What's Safe

By Cole Harlan, EditorChecked Nov 4, 2026How we verifyEditorial standardsCorrections

What SAAMI says

SAAMI (the industry standards body) published a public introduction to a new 5.56 Commercial specification on 2026-06-22. These are its words:

“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.”
SAAMI, Public Introduction: 5.56 Commercial

“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.”
SAAMI, Public Introduction: 5.56 Commercial

5.56 COMM vs 223 Remington: pressure and velocity

SAAMI maximum average pressure (MAP) and test velocity. — means no figure is shown.
Designation	Standard	MAP	Test velocity
5.56 Commercial (5.56 COMM)	SAAMI public introduction, issued 2026-06-22	62,000 psi	55-gr @ 3,400 fps
223 Remington	SAAMI Z299.4 (centerfire rifle)	55,000 psi (transducer) Z299.4 prints 550 in psi/100; GunReleases multiplied by 100.	—

We show no velocity for .223 Remington because we could not reliably read it from the PDF. This page gives no pressure figure for 5.56 NATO military ammunition, because none of the sources below states one.

SAAMI on interchangeability

“For more information specifically on the interchangeability of 223 Remington ammunition in 5.56 firearms and 5.56 ammunition in 223 Remington firearms, see SAAMI FAQs at https://saami.org/faqs/.”
SAAMI, Generally Accepted Firearms and Ammunition Interchangeability

The FAQ it points to is at saami.org/faqs.

More on 5.56 and .223

For loads and maker figures see our 5.56 and .223 ammo guide. For what barrel length does to velocity see barrel length vs velocity and the 5.56/.223 barrel page.

Which to pick (on paper)

If your rifle is roll-marked only “223 Remington”: SAAMI says only 223 Remington ammunition is to be used in it, and that 5.56 ammunition in a 223 Remington chamber “creates increased pressure and is considered an unsafe combination.” SAAMI introduction.
If your rifle is marked 5.56 Commercial or 5.56 COMM: SAAMI lists 62,000 psi and 55-gr @ 3,400 fps for that specification. SAAMI introduction.
If your rifle carries any other roll mark and you are looking at ammunition made to the 5.56 COMM specification (or the reverse): SAAMI says to contact the manufacturer of your firearm or ammunition. SAAMI introduction.
If you want the .223 Remington pressure limit: Z299.4 lists a transducer MAP of 55,000 psi. SAAMI Z299.4.

We have not range-tested these; facts below are from the makers.

Frequently asked questions

Can you shoot 5.56 ammo in a 223 Remington chamber?

SAAMI says no. Its 5.56 Commercial introduction states that using any 5.56 ammunition, including all military variants and ammunition made to the new standard, in a 223 Remington chamber "creates increased pressure and is considered an unsafe combination." Read it at SAAMI.

What is 5.56 COMM?

SAAMI's 5.56 Commercial (5.56 COMM) specification, issued 2026-06-22. SAAMI lists 62,000 psi and 55-gr @ 3,400 fps.

What is the SAAMI pressure for 223 Remington?

Z299.4 lists a transducer MAP of 55,000 psi. The PDF prints it as 550 in psi/100; GunReleases multiplied by 100.

Who do I ask about compatibility?

SAAMI says to contact the manufacturer of your firearm or ammunition for questions on a roll mark other than 5.56 Commercial (or 5.56 COMM).

Sources

Last checked 2026-11-04.

5.56 vs .223 Remington (and 5.56 COMM): The SAAMI Facts