Interesting discussion!
One thing that I've noticed while collecting guns, and gun parts, is that almost none of the old original lock parts are interchangeable. True, most flints were made before the industrial revolution and standardization became the norm, but even late period percussion locks from different makers have very little interchangeably between them.
But whether flint or percussion, bridles have various shapes and screw hole placement, no two tumblers seem to be identical, sears are different lengths, shapes and sizes, as are mainsprings, frizzen springs etc.
Basically, all the different locks are made slightly different, and consequently have a little different geometry that governs their operation. Obviously some work better than others, but all seem to work pretty darn well, despite the design differences.
John