Very interesting.  Assuming it’s not a prototype, & the one thing that suggests it’s not is the 92XX serial number.  Of course the block may not be original to the receiver.

When comparing it to the improved breechblock displayed on page 296 of John Dutcher’s book, the gunsmith had to mill out the rear of the block to make room for the new main trigger spring, make the main trigger spring, modify the hammer, make a fly, modify the main trigger & make all the components of the set-trigger assembly including drilling out both sides of the block to accept the trigger pivot pin & the screw to hold the set-trigger spring.  It appears he used the original trigger screw for the set-trigger.  Since there was no longer material to hold the sear spring found in factory set-triggers, the original trigger spring was repurposed into the sear spring.  All that took a lot of planning and gunsmithing talent.

Wayne

TomKlinger wrote yesterday at 1:28pm:


That makes sense! Thanks.