I will tell a tale I now find shocking, but sometimes ignorance teaches you what is possible.
Justnout of grad school in 1972, I purchased from an old guy my dad knew my first classic double. It was a last year Ithaca NID in 16 gauge, field grade with an incredible piece of high grade walnut. It weighed on 6 pounds and looked like new. At the time it was less than 25 years old. I paid him $75 for it since no one would even think about buying an old double then. When I got a chance to shoot it I couldn't hit anything with it. I shot it on a pattern sheet and found it was hitting 18-20" high at 30yds. Looking down the barrels it appeared to be bent upward. Ignorant of collector doubles then I didn't know until years later when I became serious that it was equipped with the lightest weight barrels and the like new barrels were only .024-.025 MWT. What I did know was that they needed to point downward.
I thought about it a little, and the newly graduated engineer decided the best thing to do was bend them back down. I found a forked sapling next to the range and used my jacket to pad the barrels in the fork and then put pressure on them and bumped then hard two or three times. Test fired and repeated once more. They hit the pattern paper dead center, and I have put more rounds than can be imagined through it over dove fields since then. No sign of the bending before or after. We sometimes forget how delicate a really well struck set of barrels cam be. These had probably been damaged in a fall or dropped, and were seriously bent. Due to the nature of the steel, they were just as easily bent back. I am surprised more gunsmiths don't attempt this with a press. I have an old Weatherby guide from the period and it has a picture of a gunbuilder in their shop with a new barrel straightening it in a screw press while looking down the barrel. I have read contemporary articles about Parker workers doing the same with barrel tubes when building their guns.