As I recall, anything over 8-10 inches is unnecessary from an accuracy point of view. That sounds short, I realize. You get some air efficiency benefits up to 12-14 inches. I use a slightly longer barrel (16) so that I can push around my bunker with it. I would actually get more shots per tank with a slightly shorter barrel, but I don't like the balls to skip off the side of my own bunker when I am tight.