A couple of questions please, is there any trigger creep or movement to release the hammer?
Can the hammer be jarred off full cock if the pistol is bumped hard with the heel of your hand against the grip or side of the frame?
I ask because my 60 Pietta required a new trigger to get the pull weight and creep free action I sought. I made mine of 0-1 tool steel and it has been reliable. Before being forced to make the new one I refit the original trigger and case hardened it several times with Kas-nite but alas it would not hold the sear nose with the hammer full cock notch.
Might want to break the gun down and check out any problem with full hammer engagement and condition of both surfaces. Some times a burr or foreign matter can inhibit full engagement.
If surfaces are correctly shaped and steel is properly hardened one can get these down to a bit over a pound pull weight with total reliability.
Once you check engagement and address any problems and have lubed the gun properly, now is the time to adjust trigger return spring adjustment. MD