oneshotonekill
I have 2 regular Encore's and 1 Encore ProHunter and the spacing on all 3 is the same, 6 inches!
I haven't tried a regular forend on the ProHunter, or vise-versa, but I suspect that the only difference would be if the contour of the barrel was different from one to the other.
BTW: My ProHunter is a 280 rifle.