While dry firing prone off bipod the cross hairs move .5” to the left. It happens mostly when I load the bipods and have a firm cheek weld. I’ve tried adjusting position, hold and trigger pull but it pretty consistently moves the half-inch to the left at 100 yards. The only thing that seems to work is no cheek weld and light pressure in the shoulder. Is this normal for the POA to shift like this or is there something wrong with my shooting technique. My groups with this gun are usually around .4 to .6 MOA @ 100 yards.