For the same price as a kit, Hammerhead will make any specific length you want (up to their equipment length) in the mofo series at least. They also have some very short stock setups.
An autococker thread hammer head kit is a great thing to have in your box. Depending on the paint and the marker, you can get some really useful but different results.
We had some bad paint/weather interaction going on (extra dry paint in extra humid weather) one day and I had an RT'ing mag. I would send out a burst of 4-5 balls at people that were standing around dodging shots. It looked like a swarm of bees cork-screwing in but all headed in the right direction. It got some good reactions, highly entertaining.