Brian. You are correct, wording in the book was about as clear as mud. I corrected it in the Errata sheet and they will send one free of charge. Just call 336-725-5955 and ask for Walker. The correct answer is that the 2nd barrel stop was used on both hammer and hammerless guns with either extractors or auto-ejectors and the vast majority 98% were used on auto-ejector guns. John Houchins.