[Raf]

Hullo Michael. No I dont know and since this is not a conventional set up it would have to be a guess. I assumed the button was the trigger release for the secondary link . In view of the early date assume sear pushed into wheel slot by spring and disengaged by front end of the secondary link pushing down on the tail of the sear arm when button is pressed. In which case the wing nut is threaded into the lockplate and when fully screwed in pushes the tail of the primary sear out meaning the sear is locked into wheel so it cant fire. But ; has the secondary effect of making sure the sear always fully enters the wheel slot. So its a sort of compromise between the single piece locking bar and the later locking bar with prop. If this is right then it implies that at this early date the deficiencies of the single locking bar were known but the problem had yet to be fully resolved . Did I pass ?