smokeeater: I believe the rear sight dovetail may be somewhere in the 3/8" range but don't quote me; if you have either a mil-spec rear sighthanging around or a slide missing one it's easy to measure - I think dovetails are measured at the base but not sure about that either.... However, dovetail cuts seem to come in varying sizes these days; mil-spec is supposed to be a consistent size cut but other pistol/slide makers often vary their cuts depending on style and size rear sight used. I believe that unless some here have collected the data you need you may need to go to the sight maker to find out what size dovetail slot they require for the rear, and possibly front sight. I know that some rear sights are meant to drift right into mil-spec slots and be secured with a small hex bolt but others are different. HTH.