Randy,
Dennis Potter (Guild Master) is probably the best at everything, but there's probably a long line of projects ahead of you. If you're in a hurry, contact Del Whitman.
Why did your rib come loose? I never heard the perfect answer as to reason, just that a fault was created in the solder joint that resulted in failure of the joint. Also heard its common when silver solder is used with rust blue barrels on a vintage gun.
My personal experience is it only happens on barrels that have been backbored, or chokes opened (although age can do it too).
All agree that not enough heat is generated during the process of backboring or opening chokes to affect the silver solder joint. But the action of the reamer (a slow load friction of metal on metal) does create harmonics in the barrel that could possibly break a weak solder line joining rib to barrels. I've had it happen twice on Perazzi target barrels that were worked on by Ken Eyster.
