I've buildt a feww muzzleloaders from scratch and want to build a doublebarrel flintlock shotgun. I've orderd a pair of mortimer lock castings from blackley and bougth two unused damacus gauge 18 barrels from Dyson. The blanks are finished machined on the inside and outside.

I'm looking for info on:
1) Joining and regulating barrels
2)How to make or buy ribs.
3)Placement of shims between barrels.

Best regards
Rolf