Thanks TW for the reminder, as I suppose I should have disclosed ammo particulars; I was using one-ounce hand-loads powered by Unique powder and loaded to approximately 8,000PSI. My gun was also fitted with Krupp tubes, but the rib extension is a separate piece of tool steel; this gun had been fired thousands of times prior to my ownership, and I'm sure the metal in that area was fatigued. I've never experienced a major problem with any other SAC gun; and the rib extension on that set of barrels have since been repaired so that it is returned to service.
By the way, the auto-ejector mechanism; and also the unique Syracuse "ejector on/off" device were the brainchild of George A. Horne; and I believe that Mr. Hollenbeck was busy organizing the Hollenbeck Gun Company when the on/off device first went into production.
Finally, as one can see I like to talk about SAC guns, and have shared a lot of unnecessary information in the process; for which I apologize. I don't understand the picture posting process here; but if anyone is interested in seeing pics of Hammerjack's Grade D Hollenbeck, I have that DGJ article with pics in a PDF file and can forward a copy to anyone provided they PM me with a direct email address.