I understand where you are coming from surely its worth a test, cut a piece to fit then give it a good welding over, clean up the bore then test rigorously to see if it fails.
I think the danger lies in this scenario - someone carries out this work and your gun is rigorously tested; it may even pass a genuine reproof and you might be happy to risk shooting it.
Joe blogs follows the same method but because of the number of variables in steel composition, quality of the welding, thoroughness of the testing, or any number of the unknown variables in hand his gun blows up and Joe is now "sans hands".
It would be all very interesting and we should push the boundaries in order to see what can be done; but as someone said, just because it can be done doesn't mean it should be done, the danger is people assuming that its worth the risk.
Today i was looking at quite an old barrel which was in a junk lot, the barrel had been cut clean in two with an angle grinder and i couldn't quite work out why someone had done this; under the rust and gunk i found that the last 9 inches of barrel was a butted brazed joint of two separate pieces, its off something quite old with a flared cannon type muzzle and it was probably shot in this condition; but i shouldn't like to.
Brazed repairs to barrels seem to be common workman repairs back in the day, i saw at the gun room quite a nice sidelever hammer gun with good meaty barrels which would have been worth restoring; but the gun room owner turned the gun over in my hand and said "yeah its just a shame about that" pointing to a massive gob of braze over a hole clean through to the bore. Obviously the gun wasn't for sale; it had come with a job lot of others he had bought.
