Thread: Rifling a Cannon barrel in NZ ?

Don't know anyone who have done so. With that sort of bore I'd look at doing it by electrolysis or you'd be looking at some rather mighty machinery, I assume you've got kit to drill the bore already.

A plastic tube wound with a single or double helical wire and with appropriate spacers/insulators, doing one groove or two grooves at a time, would be one way ahead.

https://www.thefirearmblog.com/blog/...d-printed-jig/

I saw a youtube vid a guy in the states who'd made his own breechloading cannon. The jig for cutting the rifling was based on twisting a length of flat mild steel bar (in a cold state which ensured an even twist rate all the length) and this formed the "lead screw" guide for the cannon rifling cutter, one groove at a time. Again, electrolysis seems the way to do it rather, as a 40mm bore will allow plenty central flow in the jig to flush out cruddy salt water during the process.