I've got a S&W 442 j frame and started having some internal lock issues (trigger locking up temporarily during rapid dry fire drills). Removing the lock is simple, but since I was going in, I decided to put in a wolff spring pack (8# hammer and 14# return springs) and smooth up the contact points with a 1500 grit emory.
The factory springs were 12# hammer and 18# trigger return, so that made a huge difference. It's still firm enough not to feel squishy, and sanding the contacts made it really smooth. I also replaced the factory boot grip with an old S&W Chief's Special square butt grip. I'm making a wooden piece to fill the void since it is a round butt frame gun. I'll paint it matte black and glue and pin it to one of the grips. It will look like a square butt back strap. This grip makes it easier for me to draw from a pocket and it gets my hand up higher, closer to the bore axis. This helps recoil and accuracy.
The result of the project: It fixed the trigger lock-up issue. Not been able to replicate through dry-firing. I put 50 rounds through it yesterday and from 12 yards I was able to put rounds dead on target. Now I just need to finish the grip void piece and put some bright orange on the front sight.
When I figure out how to post pics from my PC, I'll post a few. I like the old school look of the old grips on the 442.