If someone tells you he lit up a cigarette by the gas pump a thousand times and nothing happened, you might still think it's not a good idea. Here is another hint: the government does not buy or order steel cased east european ammo for the military or law enforcement. Even if it did, and you got a service rifle, then fine. But don't force feed your own baby, the one you paid for.
If your AR malfunctions with steel cases, chances are nothing is wrong with the rifle. Don't shoot steel. It is not the barrel issue btw, it is the extractor in some ARs that takes a hit. Even though a broken extractor is not the end of the world, listen to your rifle, stay away from Tula.