That Encore is a compact rifle when compared to a bolt-action rig. The Bushnell 4200 6-24X40 while a great scope is REALLY long at 17 inches. I'm thinking it would look out of place on an Encore. At 14.6 inches I do like your idea of a Nikon UCC 6.5-20 although I've never owned one. Other more compact varmint scopes that I DO own are the Weaver V-24(14.1 inches), Sightron 6-24X42(14.6 inches), and a Vari-X III 6.5-20 EFR(14.4 inches). I believe I'd pick one of those three scopes or the Nikon you mentioned. I'd also look at the size/shape of each scope. The reason I have not bought the Nikon is there isn't a whole lot of room for error between the objective and the w/e adjustment for ring mounting. FWIW.