Admittedly, beating a dead horse, but I would be real reserved and hesitant to incluce Martin Meylin as a gunsmith, period. When you research this issue, you end up with scant material and stretches, to say the least. But Meylin wasn't far from the real action, and blacksmith's tools were listed in his inventory, so he could have been a gunsmith. But look below for what is likely our region's first gunsmiths.
If you want to move beyond conjecture, then consider James Baker and his brother Robert. Pequea, Lancaster County, established by Penn Land Grant, dated 1717, 300 acres. Gunshop operated on this site. On August 15, 1719, the boys petitioned Jacob Taylor, Provincial Secretary, for approval to dam the Pequea Creek and erect a shop for making and "boaring" gun barrels. Two years later, permission was granted to mine and refine ore on this site and a Catalan forge was used here to work the metal.
Now, there's some primary documentation from Commonweath records to establish an early gunsmith. No fairy tales and no imagination applied, just the facts. Now, show us some earlier ones...primary records only, no fish stories and wishful thinking. Sam and Mary Dyke were the first to bring this material to the gun enthusiast-reading public. It's always been there in official documents. Nothing new, but often overlooked by students of Kentuckies. To my knowledge, no Baker specimens exist.
Also, look up James Chambers, (1738-1762), Paxton, Lancaster Co., PA. Killed at Fort Hunter by Indians, August, 1762. Inventory establishes gunsmithing. You can see the inventory in the book that Don and I did in 1992. Again, no Chambers guns that I know of. JWH