.223 vs 5.56 NATO

Now i know that these are basically the same chamber size but i was told that the breach pressure is greater with the 5.56 round. so that if your rifle was not up to par with this then it could lead to some bad karma in your future. On my ar-15 it states 5.56 NATO and says nothing about .223 so can i be safe to say that i will not run into any problems shooting the 5.56? as of now i have only shot .223 as that is all i have. before i buy the surplus NATO rounds i just want to make sure nothing is going to go wrong. I really wish that my owners manual answered this but hey its military issued so only covers use of NATO rounds in my rifle. any help is appreciated.

You can shoot .223 all day long in a .223 or a 5.56.

do not shoot 5.56 in your .223

Here is a link to Armalite explaining the difference.

http://www.armalite.com/library/techNotes/tnote45.htm

Here is another link to Fulton Armory.

http://www.fulton-armory.com/556-vs-223-Chambers.htm

As 7idl said NEVER shoot 5.56 Nato out of a .223 SAAMI spec barrel. If your ar15 is marked 5.56 Nato your fine you can shoot either one.

that is what i thought, I have a rock river ar-15 and as some said that the barrel for these is not marked as to what it is but 5.56 is stamped on the lower reciever.

There is no stamp just in front of the front sight base?

There should be. Where did you get the rifle from?

i was always taught to only use the type of ammunation that your gun was designed for. Guns designed for or using multiple ammuntion types make this much more difficult.

if you mean in this area

http://img.photobucket.com/albums/v3...1/DSCF0089.jpg

then no it does not. but i might be looking in the wrong area.

and i bought it at Specialty Sports & Supplies

Other side and forward between the A post and the flash hider. I have never seen a barrel that was not marked except my Bushy 11.5" upper but I have never had any RRA guns or parts. My Bushy 11.5" upper is 5.56 Nato they state that when you buy it.

If it is not marked I would call them and ask how they chamber their barrels.

Here is a pic of a colt I have that is marked like 90% of the uppers I have seen.

http://i25.photobucket.com/albums/c6...arkings001.jpg

More info here on 223 vs 5.56, with other good stuff as well.

http://www.ammo-oracle.com/body.htm#diff

my barrel has no such marking :cry: