How much space is required between the rings for the 30MM ultradot? I'm wondering if one will fit on a dual dovetail Contender base where the ring spacing is held constant, not adjustable.
I don't have one in front of me right now, but they fit my Ruger rings and they are 1-7/8" apart. The DD bases I used to have had more space than that, you should be fine.
I have a dual dovetail base and 30mm rings on hand but after thinking about it, I think that I'll just go with a Weaver base and rings. This will allow me to slide the Ultradot forward for unrestricted hammer accessibility.