Buy the Jerry K. shop manual for S&W revolvers.

I am sure it will tell you proper ways to reduce trigger pull.

In my experience, S&W has always had a decent SA pull, meaning quite light compared to others.

For my 629-2E, the SA pull was excellent, but the DA pull was horrendous and probably 15lbs+ if I could accurately measure it.

I installed an 11lb rebound spring, then modified and adjusted the tension screw on the mainspring until it would successfully rebound the trigger.

The SA is about 2.5lbs and the DA is about 9lbs now. Very smooth.