many years ago when i was a poor cop shooting at camp perry i had a "complementary" tune on my model 28 S&W by austin behlert. he was a premier pistolsmith, and offered many kinds of action jobs.
later upon examination i was able to duplicate ( for the most part ) his handywork and went on to tune other similar revolvers. this simple operation was (is) abhored by some others and you will have to judge for yourself it's value. for me, while in lawenforcement, there was NEVER a reliability issue. of course i could not sue myself. anyway here it is.
there are two items that control the heavy trigger pull, either single or double action, that is the mainspring and the trigger return spring. in my experience the flat mainspring can be reduced in width ( carefully ) to achieve a lighter and smoother pull. then remove a coil or 1.5 coils from the trigger return spring. after this work polish the reworked area smooth, and you will be amazed at the difference.
i was later sent to police armorer school and learned such modifications were TABOO, but am here ( safe & sound ) to show that they work just fine. keep a few things in mind here
1. work slow...this isn't a race. remove a little width then check the results. do some shooting and examine before and after primers. that will tell you what you want to know.
2.polish the cut coil end of the trigger return spring as well as the filed area of the main spring. this will create a smooth working part.
3.parts are cheap so have a spare before you start.
ALWAYS RELIABULITY CHECK YOU FIREARM TO KNOW IT OPERATES PROPERLY.
now i think "the kid" will probably blast me for the uncle ernie working on the kitchen table syndrome.....but this has worked for me. if you don't like the idea, don't try it(it won't hurt my feelings a bit) , but if you do it will amaze you with a slick smooth working S&W.
** as a disclaimer...this information is for your reading enjoyment only....lawyers need not apply.