All our upper receivers from the very first to the ones we are machining at this moment have the dust cover pin hole sized precisely to 0.1250", verified using a precision gauge pin. The very schematic you posted clearly indicates that the pins must be 0.125+0.000/-0.002", meaning the pin must be 0.123" to 0.125". If the pin is smaller or larger than this by even 0.0001", the pin does not conform to the schematic you have posted here. A unilateral diameter tolerance of -.002" should be checked with a precision micrometer and not a caliper as variance in caliper measurement are too great to trust when the part approaches either end of the tolerance in question. We would be happy to measure your pins with our Mitutoyo Quantum digital micrometer, capable of accurately resolving 0.00005" (50 millionths of an inch), calibrated with precision gauge blocks to +/- 10 millionths of an inch at 21 degrees C.
Furthermore, our product is not an AR-15, M16, or variant of any of those rifles. It is our goal to produce a receiver that fits as many parts available on the market as possible, but we have no control over the parts created by other companies, nor does our product conform to any mil-spec standard as it exceeds them in many fundamental ways.
G.F.
Production Supervisor
Alberta Tactical Rifle Supply