Green label guns: pre-94. slab side lower, large 2-screw front pin, gray anodizing, no sear block,0.155” fcg pins.
White label guns: pre-94. A2 lower, large 2-screw front pin, gray anodizing, no sear block, 0.155” fcg pins.
Blue label guns: pre-94. These were all over the map. A2 lower, either a large 2-screw front pin or a milspec front pin that is retained with a single screw on the left side, gray anodizing, pinned steel block. Of the guns with milspec front pin, some were drilled for the pushpin spring and detent and have the weep hole, some were not. I’ve also seen slab side guns with the sear block. All blue label guns would have 0.170” fcg pins.
Post 94 colt made lots of AR-15A2 Gov’t Carbines. Some were leftovers from the blue label guns that were assembled from parts on hand after the ban. Then Colt went to the A4 type receiver forging, black finish, restricted markings on the right side of the magwell, 0.155 fcg pins, unmilled web of aluminum autosear block. The 2010-2015’ish guns again had blue labels on the box, but are not what I’m referring to above wrt pre-94 Blue Label guns.