I just about finished the rough put together part of this project and did a test run. I got the Idea from a W frame compound slingshot Joerg made, his bull pup and some bubberband guns I was looking at. It can be used with 2 or 4 bands= 2 or 4 shots. The part that holds the pouch is like on the bullpup slingshot but it is polished steel, so you can stack up the pouches one on another and they slide off easily when pushed and can add more noches. to Load, Two bands in the front noch and two in the back. As the trigger is pulled a steel lined ramp pushes a bolt which pushes off the pouches in succession. So small amount of trigger pull is one shot, and pulling the trigger all the way is all 4 shots (which I timed at 4 shots in 30mili seconds) just depends on how fast you pull the trigger back. And it does have roller bearings. Once I get it all tuned correct I'll powder coat it back and put a folding stock. Side note. what I fired so far were some steel balls and smooth stones.