Steel is harder than brass or aluminum. Steel banging against steel will wear more that brass banging against steel, but the difference in wear is probably not worth getting uptight about. I tried some Wolf 45 quite a few years ago....very dirty burning ammo but functioned OK. Steel cased 30 Carbine broke extractors though....never had that happen with brass cased ammo. I became an expert disassembling 30 carbine bolts (yes, you need the tool to do it properly...). So, I stay away from steel cased ammo except for use in maybe revolvers or semi-auto guns that were designed for it, like an AK or an SKS....but even then I prefer brass cased ammo. YMMV, but last I knew, Gozer doesn't use it either.