Thanks for your replies and the pictures. they're exactly the kind of cracks I was thinking of.
I hear a lot about good solid BP barrels going for nitro proof, maybe to sell or to perhaps to be able to shoot more widely available cartridges. The Robinson gun is in need of a spruce up, it's not a valuable gun and the only reason I saw it was I'd been asked to re black the barrels and tidy up the woodwork. When I looked under the barrel flats, I saw the damascus where the blacking had worn away and told the owner, he's happy now as they'll look lovely browned and what with a nice oil finish he said he may send it to the proof house.(perhaps he's thinking of selling it ?) I need to get the bores measured first but I can't really see any issue with this action, just wondered how something like an 1880's Scott Baker action would cope with modern charges even if the barrels were up to the job.
The flat to breech face angle is certainly a weak point but the radius instead of a sharp right angle will spread of relieve the stress, was this figured out during the development of what we see now as the modern shotgun ?
I suspect cross bolts and dolls head rib extensions could help strengthen the joint in cases like this.
The question 'why re-proof ?' Is a good one. You could easily lose an old gun by doing so, but some older barrels have been proved to be extremely strong and well capable of withstanding modern charges, definitely two schools of thought there. As was said, a re-proof could be done for piece of mind, selling point or dare I say, just to save all the hassle of loading your own and the extra cleaning involved in using black powder.
Each to his own though. Sorry if I ramble on, I find it's hard to put down in words what I'm thinking sometimes.
