I had to do the same thing to a Sako L46. I wanted to replace the original swivels with quick detachable studs. Surprised to find 1/4x20 machine threads on the rear instead of metric threads. I simply took a 1/4x20 bolt, cut the head off and silver soldered it to a QD stud after I cut off the wood screw threads. The solder joint is hidden underneath, and with a little polishing and some touch-up bluing looked perfect. Also surprised to find the barrel channel stud was American thread, also.
