I've been wanting to try a roller gun for a while, but I thought it would be interesting to adapt some of the stock parts I had on hand, instead of building a gun from scratch. So I made up a Delrin and stainless muzzle, and will try the two stainless buttons at the rear to secure the bands. The quick and dirty slide ring was just my simple way to use an existing shaft, because the shooting line couldn't run to the shark tab without likely fouling on the wishbone arrestor pegs. This isn't intended as a long range gun, so I'm hoping the affect on accuracy will be minimal.
I chose the peg arrangement because I wanted the bands to stop before they got pulled part way around the roller and affected the spear trajectory. I'm a little worried that the pins will be a weak point, but I did use heat treated 416 SS dowel pins, which are about twice as strong as 316. Also, I don't plan to use a lot of preload, so hopefully the force on the pins will me manageable.
I thought overall that the design made for an intersting approach, because it could be a "bolt on" mod for anyone who had the same barrel and a shark fin shaft.
The gun is 42" overall, which should be about right for the dirty water I'll use it in. Grouper is closed here, and Snapper will be in another month, so this will be for those quick little mangroves on the shallow wrecks.