OK, so I took a closer look, and the mags are hitting the pin/bar/whateverthehellitis, so I ground down a bit of the feed lips, and that got it a little more in. However, it then got jammed on the mag lugs (i think), so I ground down those a bit, but then the tab came into play.
At this point i feel like it would almost be better to just make mag mods instead of touching the gun, because even if I do grind down the tab, i'll still have to do a bunch of grinding on the mags to get them to work. SO, if i was to grind down the back side of the mag to clear the tab, is this going to screw up