06-16-2020, 01:09 AM
It looks like the long pin rest in a slot of the lower receiver and held in place by a screw just to the rear of the mag well. I figure the screw holds the pivot pin in the correct location in the lower receiver. A picture of the top of the receiver would confirm there is room for the long pin to accept the bolt catch lever in the correct position. Looks like the extra screw hole is the method of retaining the bolt catch pin compared to the traditional lower receiver. This is the first time Ive seen a lower receiver configured in this way but once the upper and lower are pinned together the bolt catch just needs a pivot point because it can only move a small amount with the upper and lower pinned together.