I don’t know if anyone else mentioned it yet but the steel case of steel case ammo is only one of the problems with it. Yes, steel is harder than brass, so it’s rough on extractors, and the lacquer that is used to seal the cases gets gummy in the action. But another reason that I don’t use steel case ammo is that steel case ammo usually means all the components are cheap…cheap powder that doesn’t burn cleanly, and often underpowered, cheap primers, and cheap quality control. I stopped using steel case 223 probably 15 years ago when I opened a 20rd box and 2 cartridges were missing the primer entirely, and one cartridge had 1/2 of a primer in it….like literally the primer was sliced in half, lol. I had fired 1000’s of rounds of steel case before that, because it was cheap. Lots more malfunctions than using quality brass ammo, but that meant more opportunities to practice remedial action, lol. But I quit after seeing that one box. And I gave away a few cases of it to one of my buddies who didn’t care about it.