brennon272,

1 & 2. Perhaps purchase a AYA #2 in 12 guage. This will give you dimensions of a Holland sidelock bar action in 12guage. That and a 20guage will give you dimensions and scaling. I would also look at the back action Holland as it is considered stronger than the bar action.

3. I'm no engineer but Dallas' book on McKay Brown mentions EN series steel for action bodies and it is able to be case hardened.

4. I think Border barrels does chopper lump barrels.

5. I would recommend Guncraft by Vic Venters. This, and Ellis' book, will give you details on jointing. Some of Vic's Shooting Sportsman articles will give you some details of hinge pin replacement and jointing.

My preference would be scaled to size Holland and Holland back action sidelocks with reinforced bodies, Southgate ejectors, extended topstrap and trigger guard..............in fact a Holland and Holland Royal "clone".

"Makers to the Trade" may also have components in various stage of completion from which you could get your dimensions from.

CNC digitizing an AYA #2 would give you a huge head start. Then you can scale the images for your different calibres. It is apparent that finishing is where the real work is and this is what makes the difference between an assembled "kit of parts" and a "bespoke" double rifle.

Just my thoughts. And remember free advice is usually worth everything you gave for it!

Good luck. Please keep us informed of your progress.