One other thought worth mentioning which I have not stated up until now. The rotary bolt on the smith & I presume also on the Fox & Ithaca are tapered in two directions. inside of the bolting finger is tapered so it draws the barrel down tighter to the frame while the back surface of the finger is tapered so it securely bolts the standing breech up to the barrels. "Both" of these surfaces need to be precisely fit so there is an equal bearing upon both. As the loads increased above normal loads on this Smith that Buck was testing it may as well have been the frame flexing enough to cam the bolt around rather than the opening. Once starting to rotate the bolt the barrels could then begin to open & both forces might well work together to cause the gun to open. It would indeed be interesting to know when Elmer Keith sent his 10 gauge NID back for re-fitting of the bolt to know for sure just which surface they had to re-work.
