Yes of course one must heat a barrel to solder ribs and other parts, but the choice of which soldering alloy is very important as some silver solder(like the stuff I use in jewelry work) doesn't flow until the 1500 F mark which is not a good idea for use on ribs. Barrels are heat treated and stress relieved/tempered to very specific tolerances by the manufacturer and when you heat them too hot they warp, which is one reason why full on welding isn't used(I think). One can get extremely good bonds from shrink fitting, I(along with many others) used that to attach a drill chuck to a tapered arbor, but the arbor and chuck are produced to extremely tight tolerances from the factory so not much heat is needed(or desired) to do the job, app 300 F. I don't know how much heat barrels can withstand in a concentrated area before it becomes detrimental, and my point above was to say as much and express caution to anyone who should like to try. In Mr. Brown's book he shows a good illustration of what too much heat does to barrels, so proceed with caution.

P.s. Please excuse me if I misspelled any terms, I'm from south Louisiana and we speak differently and have a notoriously poor public school system.