Like title says I have a bushnell 3.5-21 hdmr and the scope seems built like a tank but when I went to zero rifle I notice when I put the elevation knob back on and would pull the turret to the top to be able to adjust the elevation the knob would have like a vacuum and slightly pull itself back down not lining up with the dashes. I even tried taking it back off and then back on and pulling the turret up and down trying to get maybe some of the vacuum to brake but to no avail . It is kind of annoying cause its not precise as to where I'm zeroed on which dash have any of you guys had this is issue and are the any fix of should I contact bush cs.