Attached are some rough sketches of my ideas so far...
I like the layout of the NAA conversion the most so far (I have a flexible neck
), though there's no reason a similar sliding stock wouldn't work for the Chiappa (just more work). Actually, I could bow the stock upward a bit, so when slid back the comb drops down more comfortably.
The trouble with the Chiappa's factory folding setup is that they broke the action down rather than up; great for accommodating optics/rails, but not so much for clearing the trigger guard. Short of folding trigger/takedown lever, or totally new side-folding stock, there's not much of a solution. So the shortening action would have to take place at the stock and not the frame. The pictured mod has the stock twist on single wire 180deg to move in closer to the barrel.
I also found about the NAA Ranger breaktop, which sounds positively awesome, well, were it not over 700$ and not made anymore.
To be honest, the prospect of cylinder flash/blast being obnoxious hadn't occurred to me (I always wear ear pro, and would bring some foam plugs to shoot this thing for sure), but judging by the NAA rifle build over on Rimfire Central, the cylinder gap can be closed up a bit when the new barrel is installed. I suppose that if you actually trued up the cylinder face to the barrel, you could get them crazy close without effecting reliability for the dozen or so shots you'd ever put down range without any cleaning. I also wonder if a 17HMR mini-revolver would blow the cylinder forward and tend to 'seal' itself, Nagant-style, but without the trigger force?
I've looked into older break-top, rolling block, and falling block setups, and a recurring theme is present; wow, are those things heavy and expensive. They generally appear rated for something like 223!
I think that a lighter falling or tilting block (Farquharson, Martini, or Peabody) could definitely be made, but I think it'd be a tremendous amount of work to complete.
Another alternative is the Jaco Western action, which is functional, but that's about the extent of its skills
If I decide to go to that much effort (making every single part) I think I would just go with a miniature tilting/falling block action, but built the same way using laminated plates. Probably more aluminum, though
TCB