Rimfire scopes have parallax settings at 50 yards rather than 100 yds., like scopes for centerfire rifles.
Don't be surprised if a forum mod moves this thread to the Rimfire section...
The only rimfire Sightron I know of is this one- an S1 which is highly regarded:http://swfa.com/Sightron-3-9x32-SI-Riflescope-P9198.aspx
Leupold makes several rimfire scopes and they are also highly regarded: http://swfa.com/Leupold-Rimfire-Airgun-Scopes-C113.aspx
I'm not sure if Burris makes a rimfire scope that can be purchased outside of a package deal- the folks at SWFA would know for sure:http://swfa.com/Burris-3-9x40-Fullfield-II-Rifle-Scope-P12496.aspx
Weaver makes some very nice rimfire scopes and many forum members one this one:http://swfa.com/Weaver-25-7x28-Classic-Rimfire-Rifle-Scope-P600.aspx
Check out this Kruger Optical rimfire- looks just perfect:http://swfa.com/Kruger-2-8x32-K4-Rifle-Scope-P46872.aspx