I have a barely used autococker low blow bolt.
The idea behind it is that there is a channel cut out on the bottom of the bolt that allows air to put a back spin on the paintball to give it more range.
I used it part of the day during the battle of Stalingrad 08, other then that, only during backyard tinkering. It does work. Depending on the barrel you use, you can get a very good increase in range. It worked very well with a loose fitting freak insert. The reason I didn't stick with it is because it was an air hog. You have to really turn the reg up for it to work correctly at 300 FPS. Other then that it is an excellent bolt.
They are hard to find now, especially in this condition. I even have the packaging it came in.
NOTE**** It is missing the spring and ball for the Pull pin. A while back I had acquired a bolt that did not come with a ball and spring. I had used it from this bolt, and I have since sold the marker with that bolt.
It does however have the screw that came with it. A standard ball and spring will fit.
I Want $20 shipped. Firm, because they are rare, even missing the ball and spring.