My 629 Classic with a hammer mounted pin has the sweetest trigger pull I have ever felt on a revolver. This was obtained by simply installing a reduced power mainspring and trigger return spring. I have never had a light strike with this revelover in this configuration. It is my only S&W wheelgun with a hammer mounted firing pin. On all of my other S&Ws the pin is frame mounted and it seems any time I install a reduced power mainspring I start having light strikes and misfires. Does the frame mounted firing pin require more power to make it reliable or is there some other sort of alchemy going on in my 629? I guess there is a firing pin return spring that needs to be overcome and maybe that requires more power?