We have an interesting discussion going here. I believe the consensus at this point is that we have an Upper Susquehanna rifle at hand, but I don't think we can go much further than that without guessing. I also don't see this rifle as an original flintlock. I think there is wood loss above the lock that is not conclusive with this being an original flintlock, as the rest of the gun looks like a post-flintlock period piece. Respectfully, I strongly disagree with several of the previous attributions. I can see nothing, here, that places this definitely as a Baum, Albright, Kaup, Dreisbach or others for that matter. We know it is an Upper Susquehanna rifle but without a signature, we are reaching when we select a given maker and try to make it fit.
One name that has not popped up yet that deserves attention is Samuel Morrison or William Filman from Milton, Northumberland County, Pennsylvania. Morrison usually used a handmade sidelock, but he did use commercial locks at times. Please refer to the library for additional information on Morrison and pictures that may be beneficial. I am very familiar with Rifle 292 from Whisker and Chandler's Patboxes Volume II. That rifle has a similar patchbox and the incised liness under the lock and along the forearm are identical to this rifle. Rifle 292 also has two screws, but was always a sidelock. Additionally, there is a "feather holder" under the cheekpiece on that rifle and an original pick that was presumably used with the sidelock. From mere speculation, I expect that a pick would not be uncommon to use with a sidelock, as there would certainly be more fouling associated with a straight channel from the nipple to the barrel (with the absence of a drum).
The buttstock opposite the patchbox is a classic from the Milton area and the Upper Susquehanna region north of Snyder, Union and Northumberland counties. If I were to wager a guess I would put this with Morrison or less likely with someone from the northern tier of Pennsylvania or southern New York. My guess is as good as others, but I just can't see this as a Baum, although the patchbox would fit in. Eric and I previsouly discussed Baum and I am pleased to see the amount of work and attention being placed on this maker using his original journal from a local museum and Eric's meaningful contribution. I would be curious to hear Eric's input on his recent discoveries. Albright, this is not, although I can see a common feature with David Albright, who did use the engraved star on a similarly shaped sideplate. Kaup, probably not, as the Levi Kaups usually use a different patchbox design and the Leroy Kaups would be a little late for this rifle.
Like I said before, this may be a Morrison or Filman from Milton or the northern tier of Pennsylvania/southern tier of New York. This is guess, but I think it is one that deserves consideration in this discussion.