How Tight? being not there, waiting to read measured dimensions ..
nearest 5 hundredths of a mm? ala 27.0 or 27.05


Using an adjustable reamer in the LBS , I took out just enough wall (0.1mm) to use 27.2 seatposts
in a frame made with a 27.0 seat tube bore/ID.

perhaps you still have rust, from stuck post .. brake cylinder hone and polish frame, Inside the seat tube..