In respect to "bad barrel" look at it this way. A pc of metal when straight is then heated to harden or otherwise transorm it, if not properly done may release internal stresses that lets the metal bend back to its original position before being straigtened. If heated it will probably return to its starightened form. In the cae of a rifle barel it does not have to be off very much to produce large variations in POI. It is pretty rare in a production barrel but it does happen. I hope Mr. Norway didn't get one of those.
I am relying on my metalurgical training here which I havn't used in 20 yrs so the memory may be a bit fuzzy. Any clarifications would be welcome.
El Lobo