A few years back, I watched a good friend/home-spun gunsmith (not unlike JMB himself) remove a pretty good size dent in one of my 8/81. Unfortunately, I was so new to guns and especially gun-smithing, that I had no real appreciation for what he was doing or that it was something special. Sadly he is gone now and I'm left trying to remember how he did a lot of things.
As to the dent removal, I'll try to relate what I remember but the two options are sort of contradictory. I remember thinking at the time that what he was doing was similar to taping the handle end of a hammer to seat the free floating head on the other end. Thus, if I needed to remove a similar dent, I'd try option 2 first.
1. He put something inside approximately the same size as the barrel, then formed a piece of lead to the shroud's contour but a bit bigger then the dent, he then tapped on the lead with a hammer, allowing the piece inside to knock the dent back out. He checked under the lead after each tap, after a few taps he handed it to me done.
2. He put a round piece of lead inside as close to the shrouds diameter as he had. Then placed a concave piece of over the dent protected the shroud a piece of cardboard or material and tapped it with a hammer, allowing the lead inside to knock the dent out - of course checking it regularly until we were satisfied the dent was totally gone.
Sorry I didn't take pictures and/or remember better... he just made it look so easy!! As if he did it regularly no big deal!

I can also say that to this day, I have no idea which gun had the dent, as there are no telltale clues on the gun shroud. Sigh... hope someone understands what he did and shares it with the rest of us.

Though defensive violence will always be “a sad necessity” in the eyes of men of principle, it would be still more unfortunate if wrongdoers should dominate just men. - St. Augustine