I have a NF scope with 30mm rings, very nice rings with cross bolt, lower ring is .911 at widest point and .639 at lowest point that would engage base......the bases that came on the rifle measure about .480 at widest point and .354 at lowest point and no inlet for cross bolt. Rings cannot be tightened. Are there different sizes of bases, some wider, some narrower? These mounted on M700 SA rifle. Thanks, r in w.

Yep there are nearly as many scope bases as there are scope brands.


Here are just a few
Brownell
.487 over two .040 pins, x .090 - .093 tall, serrations on left hand side of dovetail x 40 LPI, hardened material

Kimber / Brownell
.468 over two .040 pins, +/- .002, x .107 - .109 tall, 1018 material

Small Brno, # 1 -5 rimfire, and 527
.724 over two 1/16” pins, x .100 - .102 tall

Large Brno, ZG, 600 to 602 series, 550 series
.812 over two 1/16” pins, .117 - .119 tall

Old Talley, non removable clamp on scope ring, recoil shoulder of base only in front of ring.
.502 over two .040 pins, x .098 - .100 tall

New Talley, removable clamp on scope ring, recoil shoulder in front and rear of ring.
.510 over two .040 pins, x .114 - .116 tall

Griffen & Howe base.
.542" over two # 50 size pins, x .125 tall,x 60 degree dovetail +/- .002"

Normal tolerance of dovetail over pins, + / - .002” unless noted otherwise


Sounds like you have a weaver or Picatiny ring trying to mount on a Talley base

I have gone back to this thread three different times and for the life of me have no idea what he is referrring to. Is it just me?

Then no comment necessary then, from catalog pics (photos) I believe these might be Davidson (brand) bases but NF (Nightforce brand)scope has rings (30mm rifle scope mounts) that appear to be 4 screw Leupold Mk IV (Mark 4).....so maybe take scope down to store (gun shop) and see if MK IV bases might be the solution..(correct base for the rings)..........thanks & Merry Christmas. r in s.