Before you get rings, check that your scope will clear the rear sight. It made it kind of tricky on my CZ(I think the BRNO has the sight in about the same place) I tried a 3.5-14 x 50 first, the bell wouldn't clear the sight without stupidly tall rings. Part of the sight can be removed which helps a little, but not enough to get a good cheek weld. I had to settle for a set of Leupolds, that I'm a little less than impressed with, but seem to be ok enough.
