I started building my lower (aero m4e1 and aero parts kit) today since my stock should be in the mail this afternoon, and immediately I have a bit of a problem. I put the magazine release in and something is off, when the button is pressed half the time the mag catch is getting caught on the receiver and wont move, in order to get it to push I have to let go of the button and then try again until it pushes correctly. On inspection it is obvious that there is a little too much room for the "bar" of the mag catch. There is about 1.5 - 2 mm of extra space at the front (toward the muzzle) of the "bar" which allows for there to be a little too much wiggle room. I don't have a spare mag catch to compare this one to so I am unsure if it is the mag catch or the receiver that is out of spec.

Do any of you happen to know what the proper dimensions of the "oval shaped" hole for the magazine catch are supposed to be?