I tried to run another 2 33rd stick mags and was getting some fail to feed and double feed. They are the cheap Korean mags so I swapped out to my g17 17rd mag and still had one fail to feed. I am 428 rounds in. I still like the rifle and am trying to work out the bugs, I don't condemn anything until I have put 1000 rounds threw it for break in. It is loosening up a little which is a good thing. The next 572 rounds will be with factory 17rd glock mags.