05-25-2018, 12:28 AM
(05-24-2018, 10:02 PM)Belsnickel Wrote: It is my understanding that there is a variance in the chambering between 5.56 NATO and .223. There is some slight difference and that is also different between the AR-15 and the M16/M4. I want to say the neck on the case is slightly longer on the .223, meaning it can't be chambers in the military variant, but the civilian variant can chamber a 5.56.
Other way around, my friend. The 5.56mm round has a slightly longer "neck" Also the chamber pressure is a bit higher. A .223 chambered firearm cannot always fire a 5.56, a 5.56 chambered firearm can always fire a .223. It's the exact opposite of the 7.62x51mm and .308 winchester rounds.