Squirell, Nope there's not 31 rounds in it mag. I was actually able to pop off 5 rounds or so before it dropped again
kabob, I checked that and the tip of the screw is flush with the button, not recessed or protruding.
For what it's worth, I have removed the upper and they still won't fully lock in place. I had thought they may be bottoming out in the upper before the latch could engage. Maybe I should repost this in the Magpul section?? what do you guys think?