This should do fine with steel cased ammo. As with any firearm you may find it likes certain brands better than others. So I'd recommend to just grab a couple boxes of different kinds of steel cased ammo and see Wich one it runs reliably. Hope this helps.

Orvil, I happen to own two Diamond Back AR-16's and have not had any issues with steel cased ammo. I have shot Wolf steel case in polymer coated, lacquer coated and zinc coated, Hornady steel cased without issue. You can take this for what it is worth as I doubt you will be doing drum dumps to heat your rifle up to melt anything. Clean it frequently and you will be fine. Cheers and stay safe!

Orvil, DB does not recommend Steel-cased, lacquer coated ammunition. The problem with this ammunition is the lacquer coating on the case. As the barrel heats up, the lacquer turns to a soft, varnish substance and upon cool down, becomes very solid and difficult to remove. This effectively creates an undersized chamber and creates understandable problems. That being said, on the DB forum, people are reporting no problems with steel cased ammo. >>> diamondbackforum.com/index.php?topic=4140.0