12-12-2019, 10:42 PM
You might be able to tell how square the upper receiver face is by standing it on a piece of glass, smooth granite table top or other smooth surface. Use a light to see if there is a visible gap and the top of the receiver is level. If the previous barrel was centered and square into the upper you probably didn?t need but a couple of clicks of windage when sighting in the irons or optic.
I’ve moved a place holder scope between various AR-15’s and it is easy to tell which uppers have been lapped because the scope needs so little adjustment. Put the scope on an unlapped upper and you have to crank in significant windage and elevation.
I’ve moved a place holder scope between various AR-15’s and it is easy to tell which uppers have been lapped because the scope needs so little adjustment. Put the scope on an unlapped upper and you have to crank in significant windage and elevation.