.223 Remington

About .223 Remington

.223 Remington is the civilian cartridge that 5.56 NATO was built from, loaded to lower pressure with a shorter throat. In practice this is the varmint and target side of the same family — flat-shooting, cheap, almost recoilless, and the reason a prairie dog rifle and a service carbine can look so similar.

The direction of compatibility matters and is the most commonly ignored fact in American shooting. A 5.56 NATO chamber fires .223 Remington safely. A .223-marked chamber should not be fed 5.56, which runs higher pressure with a longer throat. If your barrel is marked .223 Wylde, it is cut to take both — that is the entire purpose of the Wylde chamber.