Sorry for the delay in responding, the holidays have kept me busy. I stopped by the store to ask the current owner if he had inherited the revolver with the store, but he said he didn't remember it being there when he bought the place. He did say he's heard of guns busted by chainfires, though. I agree that it seems odd that the top breaks from the bottom chamber firing. My guess is the brass frame and why we like steel more than brass. If you fire one enough, you'll notice the cylinder on a brass framed revolver fit looser and looser over time because the brass does suffer wear. Also, the balls coming from the chambers on either side of the 12 o'clock position do catch a piece of the frame.
