I recently got my hands on a Rock River AR. After looking at the ammo prices for .223 / 5.56, the ammo prices are kinda up there for decent brass cased ammo. Looking at prices online at ammo to go, I saw that they have steel cased ammo, such as brown / silver bear, Wolf, and some Hornady TAP training ammo for quite a bit less than the brass cased stuff. I have heard stories that it wears out parts within the rifle, and I've heard stories that it is perfectly fine to run it. I'm trying to run it to ground to see what it will do to the gun, and if it does wear out parts in an AR which ones.