Hello, I am new to shooting so I don't have a lot of experiences in mounting scopes and would rather not waste money buying things that will not work. I recently traded for a FNAR w/ 20" barrel. My brother had recommended looking at the Vortex scopes and I decided to go with the Vortex Viper 6.5-20x50 PA with a 30mm tube. I am now searching for the right size rings to mount the scope. I'm looking at the Vortex cantilever w/ 2" or 3" offset. I actually ordered the 2" but they are backordered so I'm looking at alternatives. I am also looking at possibly getting rings instead of the one piece, and am looking at Vortex Precision matched rings, but don't know what height to go with. Thanks for any help.