What is run-out of the turret adjustment screw ?
When adjusting your windage or elevation turrets, the reason that you should always index the turret from the same direction is because of screw run-out. Screw run-out is caused by the gap in the threads and the pitch of the threads on the screw. The more precision the screw, the less gap , however, there will always be some. This not only occurs in screws, but also in precision CNC machines, precision drill presses etc , and (in my opinion) must be addressed when adjusting the turrets of your riflescope. When run-out occurs, the per click value of the adjustment turret changes. For example, let s say that at one hundred yards, the click value of your scope is set at .25 . However, when adjusting the turret to its far end of adjustment, this value could change to perhaps .23 at one hundred yards. Correcting for this problem actually addresses and potentially solves two issues. 1) The gap in the threads of the screws which cause run-out and; 2) the possibility of sticking reticles. Let
