Ohidan,
Sorry to say, I have gone through a number of my reference books and have found 1 listing for william Mossholder in Peking, Ohio and 1 reference to him in Carroll County, Ohio and both listings were from 1880. There are George & Mary Mossholder listed who "may" have been his parents, or not, in Tuscarawas County, Ohio in 1860 and Alliance , Ohio in 1870 & 1880. There is also a Jennie Mossholder buried in Massilon. Nothing about William as a gunsmith other than a note from Tom Pike listing a rifle with his name on the barrel in script.
Mark :idunno: