Adjusting set trigger on Lyman Plains rifle.

[Jerry V Lape]

Recently bought rifle in question and the trigger would not set. The set bar wasn’t able to engage the notch on the front trigger bar.  I finally resolved that but the set pull weight isn’t really a light trigger pull.  Photo of the trigger.  There are three screws with which to make adjustments.  The large screw driver points to screw attaching the spring for the set bar.  The other points to a set screw which sets limit on that same spring.  And there is the usual screw between the triggers which I think should adjust engagement between the two bars.   What is the method to achieve a safe but lighter pull with a clean break?

[D. Taylor Sapergia]

Back out the small screw between the two triggers until the hammer trigger will engage in the front trigger's notch, and set the trigger.  Now screw in the same adjustment screw until the triggers trip.  Back off the screw again until the hammer trigger just catches the front one, and you can fine tune it from there.
The screw underneath in the rear limits the travel of the mainspring.  If your hammer trigger is being depressed too far by the mainspring and won't let you cock your rifle 'cause the trigger bar is pressing against the sear's arm, that is the screw to turn IN forming a stop for the mainspring so that the hammer trigger floats.
The screw that retains the mainspring can be tightened or loosened to increase or decrease the amount of pressure the mainspring has pushing down on the hammer trigger.  It rarely needs adjusting once the mainspring is attached to the trigger plate.

[Jerry V Lape]

Thank you D.Taylor.  That was excellent description of the process.  I haven’t used set triggers before and had not learned how to go about adjustments.