+1 on the Master Molders. I got 2 of em for about $25(including S&H) from cheaperthandirt.com. Also you don't need to modify your gun to accept theses mags. Just file down the magazine (make sure your 922r compliant though-don't just slap a 30rounder in there). I have never had a problem with them, and if I do, hell they are only like $12 a piece. They are not the prettiest mags, though, with that being the only downfall.
Master Molder mags