This is a good early rifle. Joel Ferree was killed just a stones throw downhill from where the KRA holds their annual meeting outside of Pittsburgh, in 1801, so that makes this a 1700s gun. Made where, who knows? Could be Lancaster since most of his work was done there. Probably his best work is shown in the early KRA books; it has a long barrel, a daisy patch box and very fine raised carving. I seem to recall that it sold in the last four or five years for 50 K which is still a good buy in my world. While this gun has rather simple, but excellent carving, and a wood box, it is probably one of his less expensive guns adding to the early date. The "Miller's Blockhouse" rifle is probably the same age, but has a brass,. daisy finial, box.
As to the Monmouth rifle, it makes more much sense to refer to as that, than it does to call Pennsylvania Rifles, by the name of Kentucky since we know that most were made in the former state and most likely never went to the latter state. No proof for provenience on the Monmouth gun, but the writing was done in an old hand using a quill pen a long time ago and is more than most of us ever get with most early items. Out of dozens of pieces, I have just one with some history. Not a very good record is it? And, The American origin of the latter gun turns on the maple stock and not much else. Could still be German made using American wood, though I doubt it.
Dick