I got an anti-cant level that is visible on the left side of the scope when the rifle is shouldered in my right shoulder. First, level the scope to the gun so the vertical cross hair goes through the center of the bore. Then I adjust the anti cant level from a table or bench. I put the rifle on the table with the swivel tightened down some so the gun won't move too easily. Then I set the 24" level 20-40 feet out, vertical or horizontal, on another table or armed chair with it levelled or vertical. Then view the 24" level through the scope and rotate the gun at the swivel so that you line up the scope crosshairs with the 24"level edge. So the scope reticle is now level with the 24" level. Then I adjust the anti-cant bubble level without disturbing the gun so that it shows level when the scope hairs are level with the 24" level. You have to check the anti-cant level after it has been tightened. Don't overtighten or it will damage the scope.