I'm another of the mind set that .500" wide 'target triggers & hammers', and/or .400" wide 'target' and 'smooth combat' triggers are the only way to go.
I'm thinking most later model K,L,N frame 'target' triggers are .400" wide.
S&W 'target hammers' must be exact, per frame size.
Some S&W models utilize a "floating hand", so be careful what You buy for Your gun.
To the best of My knowledge, K frame hammer fits K frame only, L frame hammer fits L frame only, N frame hammer fits N frame only.
J frame hammers/triggers fit only J frame.
Beware of MIM parts for sale....they are not the same parts as original S&W forged hammers and triggers.
Hope this helps!