Receiver Lapping??

[montana]

I have an AR on which the windage adjustment had to be almost maxed out to zero the rifle.
When checked with a lapping tool, the receiver was clearly high on one side. After it was cleaned up all the way around, the windage adjustment is now very near the center when zeroed.
All of mine get checked now, some are OK and some aren't.
After using the tool a few times, it may need to be put in a lathe and cleaned up, because the lapping compound will quickly wear on the face.

I have put my lapping tool on my lathe 3 times so far. The lapping compound will cut a groove in the face of the tool after some use. Good point Wheel horse!