My son has an older model 12 in 223 that he's trying to get to 1000 yds with (you know, kids), and he's using a Sightron SIII 8-32x 56mm, with burris signature rings (20 MOA) and a 20 MOA rail, and he can just barely do it, but the scope is at the limit of its verticle adjustment, which makes the windage adjustments wonky (according to Sightron). He could likely do what he wants with a 40 MOA base, but I cannot find one for the older "flat" rear action ring.

Does anyone know of such a thing??? At this point his only option is a scope with a 34mm tube (like Leupold MK5)... all very spendy, and then he'd lose the 20 MOA in the Burris rings... net zero gain. Or a scope with more than 70MOA of verticle, still in a 30mm tube.

He does want a variable scope of about 24X on the top end since mirage gets pretty bad beyond that magnification, and he intends to use it on his 6.5PRC for big game as well.