Doc Nickel posted this at the Tinker's Guild Forum a while back and I found it very informative. This is Doc's take on "undershot" bolts which are like Tippmann's Flatline barrel wherein they add a backspin on the ball.

Undershot bolts are nothing new. Cooper-T's had 'em for Sheridans for over a decade.

And, since so many places make undershots for such a wide variety of guns and so many manufacturers install 'em on new guns, they must be good, right?

Sarcasm aside, don't bother.

The "undershot" concept does, after a fashion, do something. It causes the ball to roll very much like it does in a Flatline barrel on an M98. This gives the ball "lift" as it flies, which adds range.

But, just like the Flatline, it's not reliable or accurate- the undershot-equipped gun becomes little more than a "cover fire" gun; all you can do is drop paint from a ways off, with the balls going every which way and generally landing somewhere inside a fifty-foot-diameter circle.

In fact, the undershot-equipped guns tend to be less accurate than even the Flatline guns, since the Unders don't have the barrel curvature to help guide the induced ball-roll into a vertical-as-possible plane.

And in any case, when somebody tells me a bolt "increases accuracy and consistency", my BS meter automatically pegs into the red zone.

We've been over that argument before... Hasn't anyone FATted some of those discussions?

Doc.