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-inch diameter jacketed bullet, with weights ranging from roughly
40 to 90 grains; the 55-grain being the most popular. Pressure is the
primary difference separating the .223 Remington and 5.56x45mm. The
.223s are loaded to lower pressures and velocities compared to 5.56mm.
Due to its lower pressure, you can safely fire .223 Rem. ammunition in a
5.56mm chambered gun; however, the same cannot be said in reverse.
The 5.56x45mm ammo creates a higher pressure. This over-pressure will
frequently cause difficult extraction, flowing brass or popped primers.
In extreme cases, the over-pressure could damage or destroy the rifle
and injure the operator. Chambers cut to .223 Remington specifications
have a shorter leade (throat) area as well as slightly shorter headspace
dimensions compared to 5.56mm “military” chamber specs. This
contributes to the pressure issues.
Join us on our
Share this page with your friends
on your favorite social network: