If you have a used LEO 96D you only need to smooth up contact surfaces. The hammer spring which for the most part affects your trigger, should be smoothed out enough. A "D" model spring is the best DA spring going as a stock item which will be reliable.
in terms of smoothing contact surfaces, if you are good at surface polishing (DO NOT ROUND EDGES OR CORNERS) then polish the contact surfaces of the trigger bar that engages with the hammer and contact the frame. Then a little moly lube on those polished surfaces. you will have a very nice trigger.
Boltgun