[rhop1mechanic]

I recently purchased a Ruger Mark IV tactical and the rear sight has 2 setscrews that worked their way up. I also noticed that I lost my zero after shooting about 200 rds. Good groups, but not on the bullseye.
I tightened the two setscrews assuming that they simply hold the sight securely in the dovetail.

 

[llamatrails]

They do hold the sight in the dovetail.

Best to use Blue Loctite on the screws to keep them from coming loose again.

My MKIV Tactical also had the sight screws loosen, and the screws for the top picatinny rail.