I learned why I didn't do this today. It's a royal pain in the butt! I didn't think it would be such an ordeal trying to make a breech. I have tried a number of things with 5/8" pipe to try and get it to fit snugly around my barrel with minimum air escaping and still be able to slide but to no avail unfortunately.jackssmirkingrevenge wrote:Even without o-rings, a tight fitting sleeve will have minimal air loss and the benefits in accuracy should be worth it.
I might grease up another 1/2" piece of copper and try to fill the void between that and some 5/8" with epoxy, but I fear the gap might be a little too small for it to flow properly.
It'd be nice to use o-rings but without a lathe it's a bit hard to put ring grooves around my barrel, and I have a feeling the action sliding back and forth will tear into them as the end of the sleeve goes off and back on to them.
I'll brainstorm (and experiment) a bit more until I find a result I'm happy with. Perhaps a ball valve with a hole drilled in the side is the way to go.