[dabbson]

Hi everyone i picked up my first AR which is a S&W M&P 15 sport chambered in 5.56 NATO, and i also bought .223 rem and shoot about 35 rounds not much. my question is can i use .223 rem in it. the only i ask after i fired them through is because i didn't notice it was only chambered for 5.56. freaking out a bit

[okdonk]

U can shoot .223 from 5.56 barrel. But not the other way round.

[dabbson]

Originally Posted by okdonk

U can shoot .223 from 5.56 barrel. But not the other way round.

yea the barrel is stamped 5.56, i used.223 UMC and it was great

[okdonk]

Don't worry you are safe! My barrel is 5.56 and i haven't even shot 5.56 ammo but had shot more than 1k rounds of .223

[dabbson]

Originally Posted by okdonk

Don't worry you are safe! My barrel is 5.56 and i haven't even shot 5.56 ammo but had shot more than 1k rounds of .223

thanks alot

[willfully armed]

In all actuality, you CAN run 5.56 in a 223 chamber.

Just don't make a habit of it.

[buffalolake]

Standard .223 can only shoot .223.
5.56 can shoot either 5.56 with normal or 2.23 with slightly reduced accuracy.
.223 Wylde can shoot either .223 or 5.56 with match grade accuracy.

[willfully armed]

Originally Posted by buffalolake

Standard .223 can only shoot .223.

Physical impossibility, or just what you've heard?

[Wilder]

The 5.56 has thicker case walls, meaning reduced powder capacity, the 5.56 has a shorter throat than a .223 chamber. A .223 is pressure tested SAAMI style in the middle of the case, where pressure readings are highest. The 5.56 chamber pressure is measured from the case neck ( might be wrong but I think that is a military method) where the pressure measured is lower than the mid point, and the 5.56 is still measured higher than a .223. Put a 5.56 in a .223 chamber and you could get dangerously high pressures. Most guns will take it and you won't notice until some number of rounds later and the metals in your gun have had all the beating they can take. You might lose some accuracy one way or the other, but the concern is high chamber pressures.

[buffalolake]

Standard .223 can only shoot .223

Based more on the safety recommendations. I'm sure a few rounds of 5.56 wouldn't hurt, but I wouldn't trust my life to it.