Well, that wasn't my figure...it was DeWitt's. I assumed it included the Germans but that seems a moot point. They were serving on the British side and were just as much part of the British forces as the Rochambeau's expeditionary force was part of the American army.
We tend to refer to those Germans as mercenaries but they weren't quite that in the modern sense. Loaning out or renting military units from another country was a widely accepted practice in the 18th century. The men on the ground were simply in the service of whatever principality they belonged to and were going where they were ordered. Oddly enough, Germans were the second choice. Before they were hired the British ambassador to St. Petersburg, Charles Hanbury-Williams, tried to hire 25,000 Russians. The Empress, Cathrine II, turned him down.
As far as locks are concerned, yes, it's likely most of the Revolutionary rifles used continental locks. We say "Germanic" but that's just a catch-all phrase that really doesn't say much. They had to have come from one of the gunmaking centers, of which there were few. Perhaps Shul but more likely the Austrian Netherlands – what we now call Belgium but, again, this really needs to be studied in much more detail than just make assumptions from looking at the tiny number of certifiable surviving examples. There is a fairly recent doctoral dissertation on arms export from the Austrian Netherlands that I have but have not read yet. I'm hoping it will shed some light on the subject
I do think most will agree that the vast majority of surviving long rifles are post-revolutionary and most of those have English locks.
As far as manufacturing capacity, Britain certainly had more machines before 1830 but the real genius of their system was a combination of high skills and a very advanced notion of the division of labor...spelled out in great detail by Adam Smith in "The Wealth of Nations", published in 1776. The biggest advances in machine tool design eventually came from America simply because, not having the huge number of skilled workmen, the only way forward was to design machines that would do the job. This was a major advance but it doesn't speak to the fact that, in the late 18th and early 19th century Americans simply couldn't compete in the manufacture of metal parts. The American way of doing things did eventually supplant the old way. In fact, to this day the mass production of parts is referred to in Europe as the "American System."
