first time I've heard of or been warned against aluminum 223 casingBrass is a metal, and that particular round is brass. That's pretty much standard ammunition. What you need to keep an eye out for is steel or aluminum casings. Stuff like Wolf, Brown Bear, or Blazer.
I've seen folks on other forums make the claim that aluminum casings may actually be worse for your firearm than mild steel, because very hard, very abrasive aluminum oxide forms on the surface of the aluminum cases.first time I've heard of or been warned against aluminum 223 casing