I've been replacing the springs on my father's 642. He is getting up in age and doesn't have the strength to pull a hard double action pull any more. Although I've worked on a lot of the older S&W revolvers, I have limited experience with those with MIM parts. I can't tell you just how much help this thread has been in getting the hand spring back in place. It can't be stressed too much just how important it is to get the short leg of that spring solidly in that blind hole in the trigger. Muchisimas gracias!