I've buildt a few singel barreled muzzelloaders from scratch and want to try to build a double barreled flintlock shotgun. I've orderd a pair of mortimer flintlock castings from Blackley. Hopefully I'll get them this spring. I have bougth two damacus barrel blanks from Dyson. The blanks are finished machined on the outside and I've reamed the insides.

I'm looking for info on:
1) joining and regulating barrels
2)How to make or buy barrel ribs.
3)Where do you place shims between barrels?
Best regards
Rolf