I think we may be forgetting that not only does a technology need to exist, but there has to be a demand, a "market" for it to flourish. I think we need to add to that the principle of "exposure" of the technology to other cultures.
In 1710 Palatine Germans were shipped from England (where they had lived as refugees) to "New America", and ended up scattered, with some in as odd a place as in the Carribean. More characteristic, a large group of Germans end up in New York, another in Pennsylvania, and a smaller group in the Carolinas.
Out of those people, the largest group was the New York group of about 3200 people. Large not only in number, but they settled very close to each other. The North Carolina group fomed the next largest "settlement" and numbered about 300. The PA Palatine Germans numbered very close to their New York relatives...but they dispersed and scattered into small communities upon arrival.
In less than ten years the German settlements along the Hudson and in New York City had reduced in number as members left for other parts of New York, as well as moving into New Jersey and into Pennsylvania.
So while you undoubtedly had German gunsmiths in the first half of the 18th century coming into the Colonies, you may not have had enough folks to support a demand for rifles..., well at least not in large numbers....
Consider then if there were so many Germans in New York and New Jersey, why is New York NOT equal to Pennsylvania in the production of rifles? It was Pennsylvania first, alone, that became the center of Colonial rifle making, followed by Virginia and Maryland. To be precise, it was Southern Pennsylvania, along the Maryland and Virginia borders that became the center for Colonial American rifle making.
Why?
First, note that the reputation for the Pennsylvania Longrifle begins right about the middle of the 18th century. About thirty to forty years after the Germans arrive...roughly one to two generations after the bulk of the first Germans land in the Colonies.
During this same time period as mentioned before, the German communities along the Hudson actually shrank in size as the Germans there began to disperse, while the Pennsylvania German communities, which started out as small, dispersed groups, flourished and grew.
Now surrounding these German settlements, are Englishmen. They have a very different hunting tradition in the British Isles than do the Germans. Rifles are an unknown technology, and big game hunting only exists in the Scottish Highlands, so the English settler of the 1600's doesn't really know about rifles, nor does he come into contact with them in the colonies, until the 1700's.
In the 1700's come the Germans with a rifle tradition of about two centuries, and the wilderness of the colonies holds big game just as the wild regions of Germany. The German answer to the presence of big game is the rifle. The Germans in New York are contained in a small area so they have only so much contact with the English, but the Pennsylvania Germans are stretched out from Philadelphia to Lancaster, to Hagerstown MD, down into Va to the town of Winchester, VA. It took a mere two decades to establish this 250 mile long chain of Germanic settlements. By the 1730's the German communities are flourishing, and they are surrounded by English communities.
The English in those adjoining communities are finally exposed to rifles, and have an excellent example as to why a rifle is a better answer to big game hunting than a fusil. It's not instantaneous... it takes between ten and twenty years for the idea to catch on... which puts the time frame of 1740 -1750 as the start of the rapid expansion of the use of the rifle in the American colonies, and why PA, followed by VA, and MD are the nexus.
If I'm correct... there were probably rifles made in the 1730's, but for a limited amount of customers, and most of those records were probably in German..., so may simply be waiting for discovery in some country archive and then needing translation.
Mostly hypothetical I'll admit, but the reason the Continental Congress authorized rifle regiments to be raised in PA, MD, and VA was not arbitrary...it's where the largest concentration of riflemen lived... and I submit the hypothesis above as to why the majority lived in those three colonies.
LD