You have a very nice, clean looking rifle. It would help to identify it if we could get a couple more pictures showing details on the gun more clearly, including:
1. clear image of complete patchbox [finial is partially hidden by bracket]
2. image of tang at back of barrel
3. close-up image of brass side plate on back side of gun opposite lock.
4. image of rear ramrod pipe.
5. close-up image of cheekpiece.
It will probably end up being a PA gun, but I've seen a rather similar patchbox on a SC rifle, so you never know for sure until you check out all the smaller details.
Shelby Gallien