Preventing jams from loose magazines.

I have a mixed bag of 30 rd Korean mags, AO 20 & 30 rd magazines, and Promag 20 & 30 rd magazines.  the Promags ar not satisfactory, and the AO and Korean ones work most of the time, but when I get a jam I push the base of the magazine toward the front of the carbine, and the jam clears.  Is there any easy way to fix this?  I have a AO carbine bought new about 1-2 years ago from the USAF Base Exchange, and Have had trouble with the poorly manufactured Trigger assembly (had to file off some of the mid assembly support so I could get the trigger assembly pin to fit the holes.  And I am not knowledgeable enough to figure out what magazine release is on the weapon (I've heard that is one of the major causes of jams).  Any Help??

Thanks, I will give that a look see, though I am not certain I can tell the difference.  Some of the magazines don't jam (mostly the Korean ones), but the rest do on occasions.

The few I remember from the range, using live ammo, the round jammed while trying to feed.  Using dummy rounds here at home, the problem is still the same, jammed rounds.  Most of them either remidy themselves if I tilt the magazine base forward, or if I pull back on the bolt lever.

All my jams occurred with the same magazines of which I have many . After a long and hard study of the problem, I determined the "ears" of the ones that jammed did not look the same as the ones that didn't jam. With a file and needle nose pliers, I got those suckers working fine.