I'm using this method to sight in my ar15. http://www.ar15.com/content/page.html?id=599 The problem is that I cannot rotate the bottom half of the elevation drum independently of the top half with the markings. I'm using a CAA detachable handle. I'm not sure if the issue is that the drum is only one piece because it is a cheaper handle. I can't tell from looking closely. But if this was the case there would be no need for a set screw. I do not want to force anything so I'm looking for any advice before I try some more force. EDIT:Nevermind. Used vice grips and a little force. It was stuck pretty tight for some reason.