Quote Originally Posted by J.Baker View Post
It pivots. If you look at that second cutaway photo under the magnification ring you will see a black square ring. That's a rubber seal/bushing that holds the rear of the erector tube in place at the back end and allows enough give to allow the movement needed when the front of the erector tube is pushed left/right/up/down by the turret screws/spring(s).

The only part that slides is that rear section under the magnification ring. When you turn the magnification ring it moves the rear lens of the erector assembly (one with crosshair in it) and it's inner sleeve forward and back. This change in distance between that lens and the lens stack in the forward part of the erector tube is what causes the change in magnification power.
Thanks for answering my questions Baker. I saw that ring but wasnt sure exactly what its purpose was, now I do.

So did a little more investigating this weekend and the front 2 holes are what seem to be really off. Determined this by mounting the Leupold 1pc mount with just the front screw and the back of base was nowhere near centered on the back of receiver. Used the back single screw on the base and it fits the back of receiver pretty good and the front radius of base fits good on the front of receiver nice, but the 2 front holes are off roughly .02/.03".

I've read that the back of the receivers can be fairly hard and difficult to tap, but after buying the leupold base I think it would be best to enlarge the threads and buy the #14 and #19 bases and modify them for larger screws.

What I dont like about the Leupold base is that with the one I got the rear ring doesnt sit on the base, it's off the base at least .005" and this is with a piece of straight shaft and I dont want to force a new scope to get it tight to base. That and with the ext. base the ring isn't any further back then the original weaver flop over rings. With the #14/19 bases to looks line the extended front Z ring will be further back from what I can see from online pics. Still not 100% confident even the Z rings wont bend the scope if rings arent perfectly in line and different offsets are used, but I think I can minimize the need for large offsets.

Thanks again for the helps guys.