No set screw, yes I'm assuming its the sear. But not knowing exactly the problem or the repair I'm concerned with getting into a situation where I'm spending way too much money having someone build a new one from scratch.
No need for a gunsmith to build one from scratch. Simply call them and get the part.
A trip to Big Timber, with a stay at the Grand Hotel is not a bad thing to do, to get the rifle up there, then let them ship it back.
