I hate cases that say GUN all over it. Get a plastic Sawzall case, use a razor blade and cut the insides out and line with foam. This holds 6 magazines on edge or 3 laying flat. You can get the plastic tool boxes at pawn shops for $5.
I keep my PLR 16, 8 mags, accessories , in an old well made lap top bag I bought at a thrift store. This set up with loaded mags etc. is quite heavy and good for transport or storage only. find one with metal clasps and sturdy straps