My old upper on my DPMS fired anything. I just changed to a new one and it doesn't seem to like any of the coated Russian ammo. I had no problems with it before. I am going to clean it good and shoot it again and try the coated Brown Bear and Wolf ammo. If it still is a problems I may have some to sell. I should know in a week or 2.
Brown Bear, Wolf, shoots fine in my AR, Mini-14, Mini-30, & Galil (Golani), The full jacketed and soft nose hunting rounds feed flawlessly but the Galil and the Mini-30 needed a little mod to fsultlessly feed the hollow point type.
Just curious, what chamber is your new upper? 5.56 or .233?