Recently picked up a Custom II and upon firing it for the first time, the rear sight screw came loose. I tightened the screw thats in the center of the rear sight but after firing a mag or two it came loose again.

Is this a common problem with Kimber? This is my second Custom II and the screw on my other one does not loosen. These are stock Custom II sights.

Mark your sight for reference, remove the set screw, drop of red loctite in the hole and re insert the set screw.