I echo the others that have said to shoot the snot out of it, first.
There are several ways to lighten the trigger pull on S&W revolvers.
Loosen the mainspring tension.
I DO NOT recommend that you do any of these things, yourself.
What I do recommend is to CAREFULLY remove the sideplate
(*Attention Wal-Mart Shoppers. . . . READ how to do this, FIRST!!! You CAN ruin the sideplate and/or SCRATCH the bovine scatology out of the revolver IF you don't know how to do this!!)
Clean the revolver 'innards' completely and lube the mating parts with a GOOD gun oil.
(Breakfree CLP. . . hint. . . hint.)
Find the book "Pistolsmithing" by George C. Nonte.
Well worth the $$$!!!
I did a trigger job on my beloved mdl 19-4, many years ago (including installing a Target Hammer and Target Trigger).
When this revolver was taken to a Washington, DC ("MPD") Armorer, to have the forcing cone re-cut, he removed all of the original springs (rebound spring and mainspring) and replaced them with factory fresh springs.
This old revolver had been 100%, ever since S&W replaced the barrel.
The springs that the Armorer installed, are in a zip-lock bag, lightly oiled, in the back of the gunsafe, somewhere.