2ndtimer
Member
Basically no difference between .223 and 5.56 brass. If you have concerns and are loading warm to max loads, be aware that some brands are heavier than others and have less internal volume. In my experience, LC NATO brass differs very little from most commercial .223 brass, while some commercial .223 brass is heavier than military surplus brass (CBC, PPU and maybe Starline). Doesn’t mean that those are bad, just that they might increase pressure due to less internal volume.MY barrel is 5.56 NATO but the brass is .223. I am starting with the minimum in the Hornady book