Have you verified that the pistol upper is not suspect by using it on a different pistol lower, with all the associated BCGs and buffers that exhibited the problem on the Aero lower?
If you don't have one available, I'd be willing to meet up at Wolf Creek Road, so that a proper test could be done.
If you don't have one available, I'd be willing to meet up at Wolf Creek Road, so that a proper test could be done.