Matabele,

Setterguy has a post in this forum about building a double rifle on a Winchester Model 21 action and he's building the action as well.

My understanding is that he's using CNC to build the action.

He hasn't posted progress photos in a while but it's a great project.

Perhaps we need someone with a 3D Scanner to scan a Back action, sidelock ejector, side by side H & H for us and produce a solid model for "circulation". More people working on it the better.

There's a very good tretise on the CAD/CAM/CNC process in #195 issue of Model Engineers Workshop magazine, using free download software, if you are inclined to go this route.