I have a fetish for the Nikko Stirling 4x28 Tiara scope that was sold in the 60s and 70s. It has an odd 7/8" tube. The scope mounts on one of them was completely knackered, and this size of mount are unobtainable. Annus horriblis you might think. But no, you can get reducer rings from American gun accessory shop Brownells online. They were not very cheap - £18 or something - but they are well made and it means the scope can be remounted in any 1" scope rings.

If yours is 7/8 I have got a spare set I can sell you, but if they are 3/4 then have a look on Brownells, they should have something.

Halfway down the page. $19 plus post.

http://www.brownells.com/optics-moun...prod18588.aspx