I think that "attribution" was created by Henry Kuffman in his "The Pennsylvania-Kentucky Rifle" book from around 1960. There has been a lot of research into the Bucks County "school" since then, and there is no evidence of anyone named Jacobus Scout who was a gunsmith. The "J S" guns were made by John Shuler, Sr. who worked in Milford Township, Bucks County in the early 1800s before moving with his family to Perry County, PA around 1810. There's one in the Mercer Museum in Doylestown, PA and several others in collections. He usually initialed the (side opening) patchbox lid, but also initialed some lock plates and barrels. I am aware of only one rifle where John signed his full name. It is in the collection at Ft. Ticonderoga.