Quote Originally Posted by Black Beard View Post
Don't forget, military 5.56 is externally the same as .223 but is designed for a different chamber. It will give higher pressures in a .223 chamber than a military rifle. It will probably also be designed for maximum velocity at minimum cost, so expect pressures to be high anyway.

BB
Our rifles are chambered/proofed accordingly by probably the most knowledgeable chap in the UK. You are smack on though. Many will get a couple through a bog .223 standard AR then wonder why it starts sticking when it gets warm.

Not all military ammo is SS109 in any event. MOD262 is also produced in brown boxes and used in matches and operations along with stacks of other variations.