You can't use the stock bolt with this kits hammer. But the kit work well once you get it setup right. A.F.A. setting it up some people have it fully working in a day others a month. Once it's up an running the back spin does give you the range.

Below is a picture I made a long time ago. I made to show someone way they should not use a ported barrel with this kit. (Yes it's bad but it did the job)

The top show the ball at rest,

The middle shows the ball getting hit with air from the bottom witch lifts the ball to the top of the barrel witch makes it spin backwards.

The bottom shows that once the air is realest from under the ball do to a ported barrel the ball falls back to the bottom of the barrel and most likely start to spin forward since you are shooting small bore paint in a big bore barrel