If you are popping primers, chances are you are dealing with crappy ammo. Olympic ammo has a pretty bad rep as far as quality goes [url]http://www.ar15.com/forums/topic.html?b=3&f=16&t=149562[/url]. I would suspect if you change your ammo, everthing will be fine. If it were the mags, most likely weak springs would cause your problems, but I really think it is the ammo.