I saw somewhere here or there something about using 5.56 M193 type ammo in a .223 chambered AR was very dangerous.

I have a 24" DPMS 1" Bull barrel upper chambered for .223.  For accuracy, I use Federal Gold Medal .223 with 69gr Sierra Matchking bullets.  Great stuff.  But for general plinking, I've been using Winchester white-box 5.56 (Q3131A) or that SA surplus from the battle packs.  Is this dangerous?  Do I need to be very specific and choose .223 ammo for this AR?  (I have two other pre-ban Bushies in normal config).  It's hard to differentiate  because places like Ammoman, for example, lists everything as .223.

Thanks for the imput,

LL

If it doesn't say 5.56mm anywhere on your receiver I wouldn't use any ammo that said 5.56mm on the box.  There is a difference between .223 & 5.56mm.

The difference between a SAMMI .223 chamber and a Mil spec 5.56 chamber is the Mil spec chamber is just slightly larger in diameter and the throat is longer. This is insure reliability in feeding under COMBAT conditions. With certain brands of ammo you may get the occasional failure to extract or feed, but to say it would be dangerous is pure and total bullshit. The safety factor of the rifle components is much higher than the any produces (barring a factory F'up in the production of the metal parts or ammo load).

To answer the question in your topic though, you can shoot whatever feeds reliably. The 1:8 twist will allow you to shoot accurately heavier bullets than a slower twist barrel. Most High Power competitors use once fired Lake City military brass in their competition rifles with no problems.