In order of preference for has to work...
Lancer AWM, AR-Stoner Stainless, PMags, Aluminum.
I tend to use PMags in competition because they are cheap and realiable and I knoow how to tell the feed lips are starting to roll out. They get stepped on, lost etc at matches as well.
When the suppressor or night rifle gets loaded up, only Lancers. The .450BM, only AR-Stoners.