We forget about the old method of working by small companies and individuals. If a part needed replacing, they made one. They didn't always keep 'spares' - even if there were any available. No. It wasn't 'the American way' of interchangability and mass-production, but many of them were darn good shapers of metal mainly using just hand tools and the occasional lathe.
That is always the arguement against the British and Belgian arms of the Civil War period. They were 'fitted' together. If it worked first time, fine, if it didn't, out comes the file and rasp. That was the way they had always worked. Pistols, in particular were each made as an individual piece, either by the 'maker' or using parts supplied by the maker/patentee. Most were 'rough finish' - straight out of the mold.
So, back to subject, if you lost your bullet-mold (easily done on compaign) and miles from the nearest town, the local gunsmith or even the unit armorer, would make one for you. He would use any available mold as a pattern - just the one, or the patents people would be on their tail!