John Rigby & Sons No. 1 Mk.III Sniper

[Promo]

Andrew, already the drawing shows the stud added to the scope tube to lock the scope in place! I think the rubber shims are only there to additionally lock the scope in place, not only by the locking stud. When the rear scope ring is fully "closed" (meaning the fixture screw has been tightened to the maximum) the rear scope ring has an approx. diameter of 25mm, so 0,4mm less than it should have. So the scope is really held in place by the rubber shims.

And Roger, it is quite clear why there are only TWO of them and BOTH at the top. If you would make three of them and all three equally spaced at 120°, you can be sure that every removal results in the need of zeroing the scope again because it would depend upon how much you tighten the screw if there was an additional shim at the bottom. So the way it is designed is the only proper way this would work.