.223 vs 5.56 for a beginner

[Indyjones65]

I am new to the AR15 and I am confused on proper ammo selection. I recently purchased a S&W M&P 15. The caliber is marked as 5.56 and I'm getting conflicting information as to being able to use .223 ammo, yes you can, no you can't. I was hoping some of you could direct me to a place to find some answers, and let me know your opinions and experience with this. Sorry if this is a question that has been answered before.

 

[Slapstick]

You can use .223 in a chamber marked 5.56 but you should NOT use 5.56 in a .223 chamber. 5.56 is usually loaded to a high pressure and the difference in the lead of the 5.56 chamber also results in higher pressures. Goggle it for a better explanation

 

[rockhopper46038]

If your barrel is marked 5.56, it is safe to fire both .223 and 5.56mm. If your barrel is marked only .223, it may or may not safely fire 5.56.

 

[paperboy]

Exactly what Slapstick said....Don't use 5.56 in a .223 chamber...Bad things could happen

 

[rockhopper46038]

Actually, I should put a caveat. Not all barrels marked 5.56 are in actuality 5.56. They should be, but I've read of some AR companies that marked their rifles 5.56 when they really are .223. So, if a barrel and chamber IS 5.56, it will safely fire .223. If a barrel and chamber is ONLY .223 (not a Wylde, or other hybrid), then it may or may not safely fire 5.56 NATO.

 

[Indy_Guy_77]

Exactly what Slapstick said....Don't use 5.56 in a .223 chamber...Bad things could happen

"Could" being the operative word.

Read your owner's manual for each gun manufacturer's recommendations.

A good argument can be made that for OLDER firearms, it's much more important to strictly follow the "no 5.56 in a .223 chamber". And that for newer more modern firearms, chances of having issues are much less. (But defining "older" vs "modern" is difficult)

For further confusion... What about .223 Wylde chamberings?

-J-

 

[giovani]

The AR15.com Ammo Oracle
www.razoreye.net/.../ammo-oracle/AR15...The AR15.com Ammo-Oracle. Everything you ever wanted to know about .223 and 5.56 ammunition or ...

 

[Indyjones65]

Thanks for the responses, I will check out the links that were posted. Everyone confirmed what I had been told, .223 in 5.56 ok but 5.56 in .223 maybe bad.