February 9th, 2017, 05:17 PM
Fire Team Leader
Join Date: Feb 2017
Location: Ridgefield, Connecticut
It doesn't take much for the lugs to not fit the grooves. If one is out of position .005 one way and the other is out .005 the other, it just won't fit. Same with the width; if the lugs are .005 wider than the design specs of the groove they won't seat. If the lugs are .005 thinner than the design specs there will be slop. If the widths are both off in opposing directions the fit becomes worse. This is the primary reason some mounts don't fit some receivers.
If only a mount were designed to have grooves to match the receiver grooves, both being filled with a glass bedding or some type of epoxy/resin mix, the fit would be perfect for any receiver, and repeatable.