Probably 42mm. The rings are designed for it, BUT, you have to realize that some scopes have more "padding" or material holding the objective lens, so the diameter of the BELL may be substantially larger...
So really it depends on the scope you buy as well as its objective lens size.
My suggestion: put your scope rings on your Mini (just the bottom halves), throw it in a case, and take it to the gun store when you shop for a scope. Try a few out for fit by setting them in the rings, decide what you want, then go back home and order it cheaper on the Internet
My leupold has 40mm. Using the Rugar ranch rings I have 1/8" clearance between it, and hand guard. Also the larger ya go the more out of proportion it will look. 2655 has a good idea of trying before you buy.