According to the book "Gunsmiths of Bedford, Fulton, Huntingdon, & Somerset Counties" by Whisker & Yantz; James Clark (1756-1841) was born in Lancaster County, PA and served as an artillery artificer during the Revolution. He may have been employed in the making of cannons. Later he worked at the Carlisle Barracks and then in what are now Fulton and Bedford Counties. He was wanted as a tax delinquent in both counties. He was fined $10 in 1822 for being convicted of a misdmeanor. In 1829 he reappeared in Hopewell Twp. Bedford, Co. He was also listed as a blacksmith in Morris Twp., Huntingdon, Co. Died July 1, 1841 and was buried in the Williamsburg, PA Presbyterian Church yard. Williamsburg would have been part of Huntingdon County until 1845, when Blair County was slpit off.
There is a photo of a Bedford style flintlock rifle on page 66 of the book referenced above. In checking the book History of "Blair & Huntingdon Counties" by Africa, there are several references to "James Clark" and even "James Clarke" in various townships of both counties. None reference anything about the gunsmith trade. there were several Clarks in Morris and Warriors Mark Twps. but none listed as gunsmiths. Due to the number of "James Clarks" it is possible some of the information listed is not about the same James Clark as the Bedford gunsmith, (just an observation).
There are still Clarks in Williamsburg, and when I have a chance, I'll see if the grave can be found.