Steel case is harder than brass and aluminum (excessive parts wear) so many folks pass on Tulammo.
Excessive wear by steel cased ammo? No. This is a myth. All ammunition cause wear on parts. Steel cases is soft enough, and often times is one rockwell harder than brass. This does not cause excessive wear faster than Brass.
Though bi metal bullets, can cause wear if you're out bump firing like a wannabe Rambo, firing thousands of rounds in one setting. Yeah, you can chew up your barrel faster.
Steel cased ammo will not damage your gun, nor wear out parts. My AK's are fed exclusively steel cased ammo, because that's all I can get in my 5.45x39's and no way I'm forking over the money for Hornady 5.45 to satisfy the magnet Nazis at the indoor ranges.
The only thing I've replaced on my AK's was a recoil spring. The extractor and ejector has plenty of life left in them.