I've used Winchester White Box, Magtech, Perfecta, Sig Elite Ball, and Federal American Eagle. Also used Hornady Critical Defense and Federal Premium HST. Initially had minor issues like you described with Magtech and Federal AE, but after several hundred rounds through my EZ, all the ammo runs fine. I've had no issues in my past 500+ rounds with repeated use of the ammo listed above. I think the springs (in the mags?) may have just needed some break-in. Who knows? My EZ seems completely reliable at this point... For range ammo, the Sig (100gr) was my favorite along with the Perfecta, followed by the Federal AE. The WWB and Magtech were my least favorite. For SD, the HST (99gr) is my favorite, but the Hornady ran fine too.