223 v. 5.56

[ksberry209]

Are these 2 rounds interchangable in AR's???? I have been looking at CMMG's and the website reads 5.56 and I looked at one in a shop and it said 223. I thought the only real difference was that 556 were loaded a little hotter. Is there really anything else??? Help I am confused....

 

[JohnX]

As I have heard the 5.56 is a slightly larger case and can cause jams in a .223 chamber. The preferred choice is to get a gun chambered in 5.56 and normally has no issues running either ammo then.

 

[#1Predator]

Are these 2 rounds interchangable in AR's???? I have been looking at CMMG's and the website reads 5.56 and I looked at one in a shop and it said 223. I thought the only real difference was that 556 were loaded a little hotter. Is there really anything else??? Help I am confused....

Buy an AR with 5.56 stamped on the lower. Both 5.56 military and .223 civilian ammo can be fired in this lower. Military 5.56 ammo brass is "heavier" (thicker web, crimped & sealed primers, slightly thicker walls, annealed necks) which means the cases have less volume than civilian cases. All of the above is required under military ammo contract guidelines. Pressures in military ammo can be as much as 20,000psi above civilian (SAMMI) maximum pressures. This assures reliable operation in full auto as well as semi-auto gas operated weapons. Military cases can withstand the higher pressures.

Caution should be used when reloading military cases. Their reduced volume can result in higher pressures when compared to civilian cases when both cases are loaded with an equal amount of powder.

 

[myfriendis410]

5.56 X 45mm NATO and .223 Remington are the same cartridge.

(From Cartridges of the World):
The .223 Remington first appeared in 1957 as an experimental military cartridge for the Armalite AR-15 assault rifle. In 1964 it was officially adopted by the U.S. Army as the 5.56 Ball cartridge M193........

 

[socalgobblerhunter]

A 5.56 chambered upper on a AR has a tighter head space so a 223 will function without any issues. Most Ar's are chambered in the 5.56 because of the extra pressure from the round which in turn allows for a more universal gun to shoot both calibers. Or you can get the Rock River 223 wyled chamber for more match grade accuracy. Either way you wont find a whole lot of 223 chambered AR on the market.

 

[myfriendis410]

A 5.56 chambered upper on a AR has a tighter head space so a 223 will function without any issues. Most Ar's are chambered in the 5.56 because of the extra pressure from the round which in turn allows for a more universal gun to shoot both calibers. Or you can get the Rock River 223 wyled chamber for more match grade accuracy. Either way you wont find a whole lot of 223 chambered AR on the market.

I repeat: they are the same cartridge. A lot of guns chambered for it are chambered loose to accommodate lower quality/looser tolerance ammunition. Pressures are set by SAAMI specification and any gun chambered for .223 will shoot 5.56mm. Period.

 

[socalgobblerhunter]

I dont think any one was disagreeing with you man. If you want to get to technical specifications there is a difference between the 223 and the 5.56 and no 5.56 rounds exceed SAAMI specs versus 223.

But to keep it simple yes a off the shelf ar chambered in 5.56 will shoot both rounds but a 223 chambered bore may have issues with 5.56 rounds due to the pressure variance in the two rounds.