I took my newly assembled upper out to zero over the weekend and quickly realized something was not right. I needed upwards of 15 + clicks of right windage to zero which while not extremely excessive was too much for my taste.
My first thought was that the upper and rail were out of alignment but this was not the case. I used a rail vice block while assembling with loctite and upon inspection the rail is still inline with the upper. I mounted a carry handle across to verify and it fits perfectly so it's not the rail alignment to the upper that's the issue.
I then started looking at the gas block and it's relationship to the rail. It appears the gas block looks to be closer to the left side of the rail and possibly ever so slightly rotated to the left as well. I've included a
pic of the gas block looking down the barrel.
My question is...what part is out of spec? The upper? The URX 3.1? It's driving me a little crazy trying to see just what is out of alignment!
Rob
Parts:
BCM Middie 16" Govt with BCM low pro gas block
Aero Precision upper receiver
Shot of barrel in rail- Note the left to barrel clearance looks smaller than the right to barrel near the gas block
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