Folks,
I do believe the Encore although in this case has a blackpowder barrel is in fact a rifle for the purposes of ATF. This is because the receiver is capable of discharging a centerfire round with the change of a barrel. Remember its the receiver not the barrel that gets ATF interested. This is not the case with my humble CVA Accura or any other solely dedicated blackpowder rifle. So in this case, I believe the limit is 18 inches!