I took Mako's suggestion and moved the upper mag window self up a little. Got out the dreaded Dremel tool last night and found a sanding disk that just fit the width of the upper window edge. Chucked it in my Dremel and removed about 1/32" to 1/16" of metal. Then loaded up the mag with 30 rounds and put in the magwell of my S&W Sport AR with the bolt closed. I rocked it back and forth to see if it would seat like my USGI mags. If it wouldn't seat I removed a little more of the upper shelf edge and tried it again. When I could rock the mag and make it seat with out slapping the bottom of the mag, I went to the next mag. It took about 5 -10 minutes a mag to get them to seat like my Pmags and USGI mags. Since I'm not going to sell mine I didn't mind doing a little fitting. They all work great now. The key is to remove as little metal as it takes to get them to seat and release with finger pressure on the mag release button. I really like the Mako mags, they're very well made and I will be buying more once the craziness settles down. I'll also be buying more Pmags. Doesn't hurt to have both!!!!!