Tim, I'll need to go back and look at some references, but there have been catalogues of the number of gunsmiths in the colonies (Whisker is one who did this, I believe) and they grew exponentially in number just like the colonial population from the 1730's through the Revolutionary War. Also we tend to think "gun-maker" when we hear "gunsmith" but many/most very early gunsmiths may have had a large proportion of work in repairs and maintenance. I know little of the South but we know that in Pennsylvania in 1740 there were perhaps 6 documented gunsmiths in Northampton/Bethlehem/Allentown areas, 4 gunsmiths in Lancaster and 2 or 3 in Reading, for example (I made those numbers up; am sure others have the actual head counts). In 1770 those numbers would be in the dozens. These numbers may be affected by customs in recording census also; perhaps gunsmiths were often just "smiths" in the early records.
There are few cases of good records and it may not be wise to extrapolate from the Moravian Christians Spring shop, but we know this shop a) had a major stylistic influence; b) was a low production shop given the numbers Oerter turned out each year (I think he averaged 16). If 1000 native Americans alone from New York to Georgia west of the settlements had rifles we'd need a lot of rifle-making gunsmiths keeping very busy to supply them plus every able-bodied Virginian. I know of no records before the Revolutionary War indicating who was supplying rifles to anyone in large numbers, other than ads in the papers of the major coastal cities, and we don't have evidence that the frontier was being armed with rifles made by gunsmiths in the port cities.
There is little disagreement that the vast majority of smoothbores purchased or traded were imported, as were mamy manufactured goods including blankets etc. It was the economic system to export raw materials and purchase made goods from the mother country. It may well be that in early years, the same was true for rifles.