I have seen old sets of locks as supplied to a gunmaker by Stanton or some such and they were nicely shaped and finished (but not fully polished) and the lock plates were of a rough 'generic' shape rather than the exact shape and size as fitted.
The gunmaker would then have filed them exactly to size and shape, applied the exact taper on the edges for a perfect wood to metal fit, made any small modifications to suit the other mechanisms and after the whole gun had been brought together by the actioner (or whosoever that particular maker used for this task) the gun would have been engraved, en suite and then hardened.!
Agree with the above but believe locks were supplied without external hammers (on that type) and then after the lockplates were fitted to the action the Percussioner would make the hammers to fit the action. Remember, most of these guns were basically unique. At best these guns were made to pattern but without any interchangeability.
