There is much controversy with respect to the interchangeability of the commercial 223 Remington with the military 5.56: What really is in a Name?
The official SAAMI position is: Chambers for military rifles have a different throat configuration than chambers for sporting firearms which, together with the full metal jacket of the military projectile, may account for the higher pressures which result when military ammunition is fired in a sporting chamber. SAAMI recommends that a firearm be fired only with the cartridge for which it is specifically chambered by the manufacturer.
The .223 Remington is a sporting cartridge with the same external dimensions as the 5.56x45mm NATO military cartridge. It is loaded with a .224" diameter, jacketed bullet, with weights ranging from forty up to ninety grains, though the most common loadings by far use a fifty five grain bullet.
The primary difference between .223 Remington and 5.56x45 mm is that .223 is loaded to somewhat lower pressures and velocities compared to 5.56 mm. The ammunition designated .223 Remington can safely be fired in a firearm chambered for the 5.56 mm, but the reverse may well result in an unsafe combination. The additional pressure created by 5.56 mm ammunition will frequently cause over-pressure problems such as difficult extraction, flowing brass, or popped primers, and in extreme cases, may well damage or destroy the rifle. Chambers cut to .223 Remington specifications have a shorter leade (throat) area as well as slightly shorter headspace dimensions compared to 5.56 mm ‘military’ chamber specifications, which contribute to pressure issues.
Using commercial .223 cartridges in a 5.56-chambered rifle should work reliably, but generally will not be as accurate as when fired from a .223-chambered gun due to the excessive leade. Using 5.56 mil-spec cartridges (such as the M855) in a .223-chambered rifle can lead to excessive wear and stress on the rifle to the point that it is (or will become) unsafe, and the SAAMI recommends against the practice. Some commercial rifles marked as ‘.223 Remington’ are in fact suited for 5.56 mm, such as many commercial AR-15 variants and the Ruger Mini-14, but the manufacturer should always be consulted to verify that use of the military cartridge is acceptable in their model rifle before attempting to use it, and signs of excessive pressure (such as flattening or gas staining of the primers) should be looked for in the initial testing whenever the military 5.56 mm ammunition is used.
Some commercial chambering's are cut to accept both .223 and 5.56 ammunition but you should contact the maker of your rifle and ask!
) I tumbled them in walnut for about an hour to get them clean, I then removed the primers and crimps and in the process of cleaning the primer pockets. Some days (if I'm real lucky) it will take me longer to clean and store brass than it does the guns I took to shoot. Thanks again!
