My buddy in AZ has been using the Royal Ordnance mags- he had to lower the holes on all of them with his two DPMS lowers and brand new Stag M4gery 16" uppers- the mags would seat with the bolt back, but would drag on the bolt and were very difficult to seat with the bolts forward. No problems with the USGI and Orlites. All fed fine before and after catch hole mods with milspec 55 grain.
The guns wanted to short cycle with Wolf and Silver Bear in the unmodded mags- in one upper they sometimes didn't even go back far enough for the case to eject, and in both the Russky stuff would kick the bolt back far enough to eject but not strip the next round or strip the round with the carrier instead of the bolt and jam. One upper still wouldn't cycle 100% with the Russky stuff with the modded mags or the USGI or Orlites- the other just ate it up. Weight differential between steel and Aluminum isn't an issue for me. Before moving to CA and selling my AKs and converting my FALS to fixed mag, all I had were steel mags, and i still distrust aluminum and plastic.
hijackThe Russian ammo seemed marginal in power- even with a short gas system and 16" barrel, which should give more dwell time and give the carrier a longer push, the buffer hit the back of the tube very softly if it hit at all. It was what I'd call a half recoil. With the true milspec surplus 55 grain ball, the buffer smacked the back of the buffer and transmitted a shock through my cheekbone, exactly like I remember my M16A2 did when I was in the Army. Bottom Line: Russian stuff is marginal for functioning, and excess friction from dirt, out of spec mags, and not broken-in new gun in can cause difficulty.
Like everybody here has said many times- use the Russian stuff for blasting and malfunction drills