FWIW, Fred Smith at Bullberry pretty much proved it out many years ago that around 20" was around the optimum for Contender carbines. Combination of their relatively slow lock time and barrel harmonics. I did some of the field testing, and every carbine barrel he made for me was 20" because of it (and those by other custom shops as well). Mine were caliber specific for my long range P&V hunting, 17 & 22 wildcats mostly, but it seemed to carry over into the 24, 25 and 26 wildcats as well. Ought to be somewhat similar with the Encores although I have no personal with them... all my Encore barrels were handgun, including the customs from 10"-15".