Have a newer project going that is showing my ignorance on several levels.

Recently mounted an older scope in new rings on a new rifle. I optically centered the erector in a mirror before beginning.

After attaching the scope, I pulled the bolt and bore sighted it at 100 yds. Problem is that the bore and crosshairs were nearly 3 feet apart. The scope has an adjustment range of 65 MOA from top to bottom, and I used almost all of it (.5X65) to zero the rifle.

The rifle is shooting decent groups at 100 yds, and to point of aim, but I wanna be able to adjust the scope if needed.

I figure to shim the scope mount. It's a talley low 1" LW. Question is, do I shim the inside radius of the ring or under the base?

Cell phone calculator indicates that I likely need .020-.025" of additional height on the rear.

Any and all advice appreciated...

It's better to shim the base

I've shimmed bases and rings and really have not noticed that one is more "correct " than the other. When Leupold supplied me with shims years ago for a Vari-X 2, the shims were for the rings.

I have shimmed the base, but that was many years ago on a Rem. 700. Was able to get the rifle sighted in O.K., never ran into a situation on any other rifle since then.

On a 700 with Leupold scope and Redfield bases and rings -- I shimmed the base just to get enough elevation to sight in (barely).. Years later the windage adjustment screw on the Redfield base sheared off so I changed over to Leupold rings and bases (non-adjustable), Without shims, the scope was almost perfectly sighted in when the crosshairs were centered (be moving half the adjustment distance with the elevation and windage dials). Surprised me.

I much prefer shimming the base, but only on a one piece. Shimming two piece bases puts stress on the scope tube.

Not necessarily.

If there's enough vertical mismatch without the shims to cause the mentioned 30+ moa error with the scope adjustments centered, then it's a good chance that shimming beneath one of the bases to bring things in line will reduce stress on the scope tube.

OK, thanks guys...

Good luck.

Called Talley today to get their opinion on how to handle this.
Long story short, some guy name of Gary said to let them know what height ring I needed and they'd make it for me.

Thinking this should take away some of the confusion of what to do.

Depending on the type of bases and the gun they fit, sometimes switching front to back will solve the problem

Pretty much the guy that runs the show.....

johnw,

Was out of town visiting friends.

I've mentioned in other places how Talley will machine rings to fit individual rifles, so it's good to hear you got hold of Gary.

John,

Are they machining a cant into the rings?