Rhys95,
You must remember that on double rifles each barrel was bored rifled and chambered before the barrels were joined and regulated. What you are proposing may be possible but it will require an enormous amount of luck to get both barrels to shoot anywhere near the same point of aim.
Soldering in liners may also be detrimental in that you could loosen the ribs and perhaps even the barrels. Epoxy would be the best way of fixing them in place. Drilling and Reaming out the original barrels is no job for an amateur as they diverge and would require extensive setting up operations for a machinist to do the work. Having it done by a gunsmith would not be cheap. Sorry to put up a raincloud over your idea, but it isn't at all an easy job for anyone to do.
I'd go along with the suggestions of Lagopus (above). Relining the barrels would devalue the rifle and cost you a lot to do it. It's simply not worth it. Finally Rook and Rabbit rifles were all low powered, and therefore low velocity. When rook shooting the young birds (called 'Branchers') were shot off the tree branches upwards of 80-120 feet off the ground a miss would result in the bullet slowing down rapidly and reducing potential injury to people and livestock in the vicinity, A lot of this shooting was done in village churchyards where Rooks frequently nested, so it was a potentially dangerous form of shooting.
Harry
Last edited by Harry Eales; 04/12/14 06:44 AM.
