My goal here is to build a gun for open water. Not blue water for tuna and such, but hefty enough to handle three 5/8" bands for longer shots on mid water snapper, cobia, AJs, etc. Possibly upgradable with a fourth band if I have the chance to hunt wahoo or something.
So I opted for a hybrid design for good maneuverability, but with a little more heft to handle the extra band load. My logic was that if I could make the tube a little larger and thicker, but with a built in open track, then I could keep the height about the same as a RA barrel, and maybe even less than a typical 1-1/4" barrel with a stuck on track.
Well, for better or worse, here's what I got so far. It ended up just a hair over 1-3/8" OD (1.420"), with a built in track for a 5/16" shaft that is close to half the shaft deep, and a wall thickness that is just a little over 1/8" (about 0.140"). Sitting next to a Rabitech barrel, you can see that the height to the top of the shaft is just about the same.
I'm sure that it isn't as perfect as a production carbon fiber tube, but hopefully the extra diameter and wall thickness can compensate.
Here's the process, if anyone else has the itch.
You'll need a core of wood, foam, or something else. I tried a couple of different approaches, but the one that ultimately worked best was using one of those router bits that cut half a circle in one pass. Just make SURE that the square piece you start with is accurately planed square. Cut a groove in the top, that will help form the open track. You will also need a little "dummy" piece, wrapped in tin foil, and temporarily screwed to the end of the dowel. This will be pulled out later, leaving a recess to fit a muzzle.
You will need a half round piece to form the outside of the open track. I played with both teflon and delrin, and found that the delring works just fine and is much cheaper. Go with white, as it will be much easier to see against the black carbon fiber later when laying everything up. I built a little jig out of scrap plywood that makes it easy to cut this in a mill or drill press. You feed the rod from the left. It passes under the cutter, which removes the top half of the rod. The screw pushes down on the flat, and keeps everything from rotating as you push the rod through.
Next post, putting it all together.