As I read the original post, the 26mm rings are on the rifle and the plan was to put a 1" scope in them. Some kind of shims should be available to make the 1" tube fit. The top of the line Lyman hunting scope back in the 1950's was the Challenger. It was, still is, a good scope, and it had a 26mm tube. They can sometimes be bought cheap. I know this is not an answer to your question but a workable solution.