Trigger job?

My 1884 has a very hard trigger. It's been cleaned and greased which helped somewhat, but it doesn't last for more than 40-50 rounds.
The sear is deep in the 3rd notch and I was wondering if adding a shim is common to reduce engagement a tad. It looks as though there would be enough clearance in the lockwork.
Has this been tried? I'd rather not stone an antique if a reversible method works.

Thanks

You can replace it with an aftermarket sear and grind it to what you like, -$12 from "S & S" or buy an officers set triggers,-$110 from "The Rifle Shoppe". but those original rifle triggers weren't meant to pull easy!