[Rustywreck]

dang, that was going to be my next question. Just kidding.
I'm not much of a rifle guy, I do mostly archery. In archery, the same draw weight, same arrow will have different velocity depending upon draw length.
In comparison: Arrow weight compares to bullet weight. Draw weight compares to caliber/powder. Draw length compares to barrel length.
So in archery the clear and only answer would be yes.
It seemed to me that the longer the barrel the longer it would be under pressure achieving more velocity. But hey, that's why I ask you guys who know what your talking about, cause I don't.