This design, with a different adjustment screw, appears in George's "English Guns and Rifles". I have made several for pistols and one form my swivel breech. Its by far the best SS trigger I have come across.
Dan
Actually it is fundamentally different than the one drawn in George's book. The one shown by George adjusts the release by adjusting the sear engagement. This design has a fixed sear engagement and the release force is adjusted, rather than the sear engagement. The release force is a fixed quantity in George's design.
I thought it was like the one in George's book as well at first, but after doing a detailed layout I realized it was fundamentally different. The sear in this design is not neutral. The force created by the reaction of the main spring force acts to force the sear open. It must be balanced out by the strong sear spring force to keep it latched. The diagram in George has the main spring force acting to keep the sear latched, i.e. neutral, it will not trip because the line of action of the reaction force from the main spring creates a closing moment on the sear, it will always stay latched even without a sear spring. So the only way you can make George's sear trip is by pushing it with the trigger, so the friction in the action will create a perceptible force, and consequently, perceptible creep. Whereas this design shown above uses the main spring force to open the sear, so the sear engagement can be kept large, and there won't be perceptible creep, as the trigger flies away as soon as you upset the balance between the sear and main spring.
Mike
