Its OK for a bolt gun or a gas piston type rifle. Not the hot running AR. And what is even worse, is that it leaves it gunk in the chamber if you change to a different ammo. It makes regular ammo stick in the chamber too.
Steel cased ammo is ok to fire in an AR. The new ones are polymer coated and supposedly ok. Even the old ones are ok; they don't expand into the chamber like brass, so the chamber gets fouled with carbon; if you clean the chamber well, you'll be fine to go back to brass. If you don't, you'll have FTEs with brass.
I like MFS steel cased ammo. It is zink plated and feeds/extracts better then the polymer or lacquer coated stuff. I believe Silver Bear is also zink plated.