The Leupold Mark 5 is a 35mm scope tube. It takes a special shooter, rifle and a special bullet to get any kind of accuracy out of it at that range. 223's are not known for 1000 yds. You could put a .005" shim in the back but my first question is, what bullet is he shooting? Have you run a dope chart to see exactly what you are dealing with? I don't think a 40 moa base is a good thing with that long scope...unless you want to raise it up substantially.
Bookmarks