manny,
its good practice to lube up the rails to get a silky recoil.
also lube the trigger bar (part #32) where it meets the disconnector (part #42) and interrupter (part #39).
i like to lube the "recoil spring guide rod" since it is polymer rubbing against a steel slide.
remember a little lube goes a long way so don't over do it.
cheers,
-andy