A few months ago I acquired a Pecar 4x scope with a 26mm tube on a used rifle. The rings with it were 1" and dented the scope tube.
The scope is very nice optically and I wanted to use it.
I mounted the scope on an old 270 in some very old no-name rings that were sloppy enough to fit on the tube and not damage it. But the cross-hairs were off center with the rifle sighted in (it is an old scope).
Mule Deer suggested that 1" Burris Signature rings with the plastic inserts would fit the 26mm scope. He was right!
I used Burris inserts to center the cross-hairs with Burris Signature rings on the 26mm tube. It took a little extra effort to get them on but they work without damaging the tube.
So if you have an old scope with a 26mm tube and want to mount it with relatively inexpensive rings that are both windage and elevation adjustable then try the Burris Signature rings with inserts. (I used the Zee version that uses Weaver bases.)
Talley makes 26mm rings but they are not adjustable and are more money than the Burris Signature rings.
MD's suggestion solved two problems I had with the old scope, a 26mm tube and non-centering reticle. Now I have a very functional old high quality scope working as designed over 50 years ago. It is on an equally old or older Husqvarna FN actioned 270. Vintage rifle, vintage scope, vintage caliber and vintage shooter!
Thanks Mule Deer!