Remember some articles that stated the cause of the faster barrel wear is not the steel case but the bi-metal bullets that are usually found in steel case rounds
Yeah, a lot of imported ammo is steel jacketed with a lighter wash of copper than they should have, and some off-brands reputedly have a harder steel jacket than they should have. Then there's the quality of the barrel steel on some ComBloc rifles, chrome-lined or not.
Problem is, everything I've seen is anecdotal, so I can't say for sure what the real story is. As for myself, in my
good rifles, I follow the old adage "Don't shoot ammo that comes from a place that you wouldn't drink the water."