Right ... these stories about Henry's gun factory there go back a long time. Jordan's bio of Henry (1910) states that the factory was “on Mill Creek, outside the Borough of Lancaster, where what is known today as the ‘Old Factory Road’ crosses that stream” and lots and lots of writers since have repeated this. In a vast correspondence from 1937-38 held at Jacobsburg Historical Society, L. D. Satterlee expended a lot of effort trying to track down the supposed Henry gun factory--finally concluding that there was “something very mysterious about that rifle factory.”
There may very well have been a factory there, but it wasn't a Henry gun factory. The mistaken belief that he was producing arms in a factory setting during the Revolution has sent many a researcher searching for the factory where he did so--and so that one on Mill Creek has "solved" that problem for those who have been searching.
But of course there's no problem of where the factory was once one accepts that Henry wasn't producing guns after 1760.
