I just purchased what I would consider my first long range scope. Mark 4 6-20x50, brand new. So the scope came in and I got it out of the box and checked it out for a few minutes as soon as I got home. The lines on the sidefocus knob were not matching up so I worked it back and forth and when I rotated counter clockwise I noticed it started to unscrew. I figured that this was just the outer cover of the knob and continued to unscrew it. Then to my disgust, the knob unscrewed to the point of breaking the seal and releasing the gas. I realized that this was stupid of course and at the moment wanted to kick myself directly in the butt for screwing up my new scope. Then I looked through the literature that came with the scope expecting to see something that said..."attention all dummies......do not unscrew the SF!" but nothing. Then I got disappointed that Leupold would make a scope that would do that. Why would the SF knob not lock into place? Why not a little warning for dummies like myself?