Hammer block(trigger housing) design

[Joseph Scott 0]

This may not interest some but I will expound on the hammer block design and machining. it looks simple but is actually a complex piece of machine work. From a forging, first cut must establish a base line which I suspect is the back of the lug against the recoil key, then the flat top side is cut and then both sides cut with dual cutters spaced apart. With these flats made, the work can then be held in various jigs. Various holes then drilled all the way through using hardened drill guides for precise locations. Then the top would be milled out using several size cutters. Inside the bottom are side protrusions which hold and guide the trigger bar. Milling must be done to leave metal for them and then a flat bottom saw was run under them to undercut. At some time, a saw cut was made to allow the trigger bar to go in. Then a drill and milling cut made for base of hammer spring. The ends were milled square and to length and drilled for magazine pin. A mill cut for the safety was made inside, the grooves for the sliding fit to receiver was milled with a thick saw. There was a broaching step for a square hole towards front. The little slots for the bolt catch were made. (I just don't see how that might have been done). Also the bottom lug was threaded for 1/4-28 screw. I am sure I missed lots of steps but it is a very ingenious piece of engineering and machining. It may have taken as much work as the receiver and large number of mills, drills, cutters and jigs. A jig designer is probably more important than the machinist running the machines. I wonder if they might have been subcontracted as I can't see a small company doing thousands but I don't know how much machinery they had. Long winded but I hope informative.

[M48TANKER 0]

Joe, I saw a trigger housing that was just a bit different from any I've seen before. It had two opposing "sear" hooks. They were separate and the forward one was spring loaded and slid on a small plate. To me it appears that this must have been some sort of design for full auto firing? Were any ever made this way? The one I saw did seem to look like it was done at the factory. I don't remember seeing any way to "select" the second sear hook....this must have been done with a separate lever or switch. All the other parts in the hammer block were identical to a standard 1941 Johnson JSAR.

[Joseph Scott 0]

Not sure what that was. I am not very knowledgeable about the LMG's, however the ones I am familiar with do not have a separate hammer block, everything fit inside the lower. Did you mean the trigger sear hooks or the hammer(trigger) block housing? They did a lot of development work and it could have come from a later version. Just don't know.