Rich,
Ah yes, the elusive gunsmith Jacob Row. Like you, I suspect some sort of connection between Jacob Row and the Laudenslager gunsmiths from Union/Snyder County, PA. Gunsmiths Samuel and William Laudenslager both had spouses from the Row/Rowe family. Samuel married Esther "Hettie" Row, and William married Anna Row. Maybe they were sisters or cousins? Despite investing a lot of research hours, I have not been able to firmly establish any sort of links between any of these Row family members. To further complicate matters, there were at least a couple other Row gunsmiths from the same area. There was a gunsmith named John Row (1810-1868) from Union/Snyder County that removed to Summit County, OH, and later to Elkhart, IN. How does he fit into the mix? Dalas Ewing, Upper Susquehanna longrifle collector & researcher, provided information regarding a gunsmith named Elias (or Isaiah) Row. He stated that Elias Row signed his guns "E * R" or "E Row". I've also wondered if there is a family connection between the Row gunsmiths from Union/Snyder County and gunsmith Nathanial Rowe (apprentice to John Armstrong) from Emmitsburg, MD? Maybe someday someone will straighten out these Row's. Pardon the pun. Thank you for posting photos of this rifle.
Mark
P.S. - Do you happen to have a clearer photo of the signature on the barrel of the Jacob Row gun?