5.56 vs 223

[Mr O]

Hi Brothers in Arms,

I've heard that it's better to buy an Ar chambered in 5.56 (Marking on the FA says 5.56) instead on buying an AR chambered in 223. Apparently with a 5.56 chambered AR, one is able to shoot 5.56 and 223 rounds with less failures, the one chambered in 223 sometimes fails to feed with the 5.56 ammo, what are your thoughts?
I can't see any difference between 5.56 and 223, other than the markings.

I own a Norinco chambered in 5.56, no jams/failure to feed when using 5.56 and 223.

[Tetelestai]

Difference in pressure specifications between 5.56 and .223. Also, the chamber dimensions are different as you can deduce from your opening line. The differences between 5.56 and .223 has been discussed previously on the forum, do a search and you'll find discussions by people much more knowledgeable than I am.

I've seen a Norinco CQA repeatedly choke on the hot Indian milsurp ammo that we had available some years back. My Daniel Defense kept ticking over* being fed the same stuff. There is most definitely a difference in performance.

* - On another occasion, the extremely hot Indian milsurp blew a primer through the firing pin hole of my Daniel Defense, jamming the firing pin solid. That ammo was HOT. Non-uniform primer pockets in the cases didn't help either.

[Dale SH]

https://en.wikipedia.org/wiki/.223_Wylde_chamber

[stefanvan]

http://www.saami.org/PDF/SAAMI_SafetyReminder.pdf

[Zuku]

Interestingly you can shoot a 7.62 in a .308w but not the other way round. When going to the smaller caliber its is also reversed

[Andre in Alberton]

So the moral of the story is get a 5.56mm then u covered for both