Amazing machine work. I know little (read that as nothing) of the CAD/CAM whatever machinery business. I get by with a little knowledge and minimal skills on a manual crank machines to suit my needs. This stuff is way over the top!

A question,,is the Win21 action single lug bolting system sufficient to handle the job?
I'd guess factory 45-70 and like pressured loads may not be a problem. The 21 has a lot of leverage in the long bar.
But other rounds that generate higher pressures seem to have given other builders problems.
Seems as though Galazan beefed up the locking system in some way on his 21 DR builds. I talked with David Yale when he was building a 7x57R on a Win21 a few years back. I don't think he ever did successfully complete the project dispite several changes to the design.

I've seen a couple of Parker's done to DRifles and sucessfully so with their single locking lug. They were in 30-30 and in 38-55.