I own a DPMS 20" Classic A2. DPMS reps verbally confirmed to me that their barrels are chambered to handle both 5.56 and .223.
I have shot Federal XM193 5.56 without issue. It is hotter than the commercial .223 rounds and the rifle loves it. I am aware that Winchester 3131A (IMI) is similar in spec, but have never fired any.
I have also used Federal American Eagle, UMC and Winchester 40rd Value Pack FMJ .223 ammo without issue. While all appear about 5-10% cooler than the XM193, all have worked well. I have not tried S&B.
Some forum members have said they have not experienced problems with Russian 223 (Wolf, Bernaul, or Silver Bear), but I have made no effort to even try it. I am generally suspicious of foreign ammo, don't trust their QC. Finally, one bit of wisdom from my gunsmith ... weapons are generally designed and built around the ammo available in the country of origin ... firing an AK47 or SKS, use Russian ammo ... firing an AR15, use American style ammo.
My general rule is to buy American ammo in bulk when it goes on sale ... I figure if I'm shooting a quality weapon, I should stay with quality ammo, and do my best to minimize cost.