Gentlemen: I have mounted scores of scopes over the years. I would like to think I have it down pretty good, as I have never --until now- had any issues at all. That being said....
I recently took a Springfield Armory 6X24 Government Model I have had on this particular rifle for the last 15-18 years (and has performed famously!!). I replaced it with a Nightforce ATACR 5x25. The rifle is a Remington PSS (.308), factory barrel and trigger, with a D.D Ross (20MOA) one piece base. I left the rings on the SAI. The day before I removed the SAI scope, I was dinging 600,700,800, and 900 yard steel with relative ease. That combination has worked flawlessly for well over a decade.
When I installed the ATACR, since it is a 34mm tube, I had to run to the local Sportsmans Whorehouse and grab a set of medium height rings. Warne rings were all they had in that diameter.
I mounted everything as I have done numerous times before, and went out today to zero it. At 50 yards, as I was bore sighting the old fashioned way (no lasers), I learned right off the bat I could not adjust the elevation low enough , AND it was almost all the way to one one of my windage adjustment!!! I did check the Zero-Stop and eliminated that as a reason.
I would like to think a pretty fancy scope like a Nightforce ATACR would NOT be the issue. From what I have read over the years, the D.D.Ross base is top quality, and I have read really good stuff about the Warne rings. And, to weird things out, as I mentioned, the rifle was shooting fine before I took the scope off.
Where did I goof up? Could it be possible I don't need a 20 MOA base since the ATACR is supposed to have a butt-load of elevation? But that wouldn't explain my windage issue.
Something is not right, but for the life of me.....I can't figure out where.