Have you replaced the strain screw?
My original strain screw in my 19 was over 1mm shorter than a blued OEM replacement I picked up from MidwayUSA. You can also get an allen-keyed headless screw that’s the same thread pitch as your strain screw.
The longer screw can help establish more consistent ignition with the Wolff spring. Also, using Federal Primers helps.
A Wolff Reduced Power spring in a K frame and a 13 lb rebound spring, after some minimal india stoning on the factory parts to smooth burrs, yields a 7.5 lb trigger with a firm reset. But, the gun’s limited to Federal ammo. The Standard Power spring should crack almost anything and give you a 9.5 lb trigger.