I just went the same route with a 686-4. The previous owner had mounted a scope, lost the rear sight, etc. I ordered my parts from Smith which I installed relatively easily. But I have one annoying problem---the rear end of the sight isn't sitting horizontal. It is tipped slightly clockwise.

Prior to installing the sight, I placed the blade in the track in the frame and moved it back and forth. It appeared to move easily and left light rub marks in the bottom of the track. That suggests the blade should have bottomed completely when I tightened the front screw. I even gave the blade a rap using a hard wooden dowl as a drift to make sure it was seated. No change.

I've been doing my own gunsmithing for over 40 years, and solved a lot of problems. But this one has me stumped. Unless the sight track wasn't machined square with the sides of the frame, I'm at a loss why the sight isn't sitting horizontal.

Has anyone else run into this problem and found a solution?