Last year I bought a set of no lock 642's. I wanted a sort of matched set for wearing while i ride my motorcycle. Basically I can use either hand while riding.
The trigger pull on one of them was down right gritty and terrible out of the box. I took them to my local gunsmith who does j frame action jobs to smooth them out. When he opened the one with the terrible trigger, he found a part of a Jolly Rancher candy wrapper in the action. After he removed that, he replaced the factory springs with Wolff springs, and polished the action a bit. They are both now very smooth with about 8.5 pound trigger pull. I know 8.5 pounds sounds like a lot, but under the stress of an armed encounter, it will be nothing. I'm always amazed at people who think it's really good to have a match-grade trigger on a personal defense weapon. IMHO they are just asking for an unintentional discharge.