Gene,
Back in the day, it was not a problem to give out of proof barrels to a gunsmith to re-bore and re-proof or re-sleeve if the original tubes were too far gone to save.
Unfortunately it was found that some less scrupulous purchasers were re-selling or exporting out of proof guns leading to the proof house insisting that auctioneers cut the sides of the barrels at 9 inches so they are only fit for re-sleeving.
If you own an out of proof gun, there is nothing (apart from the cost!) to stop you getting it rebored and re-proofed a bore size or two up,
Keep Well
Parabola
