I had a Weaver K 2.5x20 on mine, and also a Leupy 4x28. Both seemed to do the job with no real complaints.

As for a variable, I like VX3 1.5-5x20 and VX2 1-4x20 on lever guns. I have owned a couple of each.....

http://www.youtube.com/watch?v=UrgpZ0fUixs