One of the most interesting tidbits on later PA rifles that I've encountered recently comes compliments of the researchers at Jacobsburg Plantation. It comes from primary documentation that they found on this historical site--the location of the Henry gunworks for several generations.
The point of interest--when the Henrys had an urgent need for hardware, they would ask for help from Henry Leman of Lancaster, and vice versa. If Leman needed something, he felt comfortable calling the Henrys, on his cell, I think. No surprise here; good businessmen cooperate for mutual benefit, then as now. Perhaps we could entice Tim to elaborate on this situation. He's got the details. Incidentally, if you want to see nice rifles and learn about them, you owe it to yourself to pay a visit to the Plantation. Open weekends, I think, during summer/fall. Not far from Easton, PA (on NJ border--other side very gun unfriendly). Close to Dixon's. Very desirable experience for historians/rifle enthusiasts.
Also, as most of you probably know already, there were certain pieces of hardware that both factorys made that were widely used by other builders up and down the Appalachian range and beyond. For instance, Henry Leman must have made tons of those cap boxes that look like a toilet seat. I owned one of the better John Shells that had this box. Shell engraved it, but I am convinced that Leman made it, as I have the identical one on a Leman rifle. That commode lid pops up on Dauphin guns and late Lancasters a lot. My bet is that H. Gibbs, Sr. and Jr. also had a give/take/trade relationship with Henry Leman, too. I ask the Tryon experts, was there a connection here, too? Just curious.