I have a colt 22semi handgun, it has a set screw that holds the rear site tight for windage adjustment. My set screw is gone..called colt from the # in the manual, they gave me another # for colt parts. Their simply reply was we don't have it. I asked what size the screw was, and their reply was we don't have that information. Customer service..NOT. Never had a issue with Smith, Ruger, or RCBS.