I'm a firm believer in paint to barrel match, I've noticed that when doing such( usually end up using a .684 freak bore) I can far better consistent fps with a 3-+ diff. If I go standard lg bore ( .693 ish) my fps will be a 20 fps drop on avg.
I'm using a pump yes, S6, with 16" freak AA barrel. I've done same experiment with my etek too, chronoed with stock barrel ( .693) at 280 fps,
Then swapped out to a .684 and fps rose to well over 300 fps. Adjusted velocity back down to 280 then put stock barrel back on and velocity was down in 260 range.
Theory and opinion - matching paint to bore helps on efficiency . I can do almost 15 pods on a 68/4500 tank filled to actual 4500. Weather this is avg or low for a pump. Eh I know I can shoot all day pretty much.
Hope this helps in any way
BLITZKRIEG DESIGNS-PAINTBALL GRAPHIX