there are variations of the triggers, early skinny, and later ones fatter, there are different heigths of the hammers, shorter as well as taller, and of course the OM Super had a wide spur...all the other lockwork ( innards, small parts) are the same, the center pin ( base or cylinder pin) also has various lengths, and the notch ( grooves) around the front portion have various widths and number of grooves, as well as some larger frame guns have a shoulder on them.....all explained in the various books put out over the years on "old models".....had a picture of the hammers from Forum member 'weaselmeat gravy' (Bob L) in my old computer, showing the hammers side by side....................hhhmmmm :? :wink: