First off, I would like to thank all respondents for their thoughts and information on the Krider 7 bore. I never even considered that the rifle may have been built in England, or possibly at least the barrel and lock. I have included some additional detailed photos in response to questions raised. The barrel appears to have English proofs, although I hasten to add, I am no authority on such proof marks. I am also of the understanding that American riflesmiths did not proof their barrels. I am also well aware that many, if not most, riflesmiths did not make their own barrels, at least not when this rifle was likely built. However, the lock face is clearly marked "John Krider," and the breech is marked "Philadelphia."
I will hasten to add here that even if the rifle was not built by Krider, but rather imported, the question still remains why?
Regards to case hardening, yes, it does appear to have possibly been redone at some time, but then again why, as the barrel and stock appear absolutely original.
On another note, one responder asked about twist, which I have not attempted to determine. That said, the previous owner clearly shot the rifle, as it came with cast round balls, a modern mold for same, and load instructions - 8-10 drams (225-250 gr) with a hard card over the powder and then the patched ball. The claim is for 1500 fps with 6,000 ft. #s energy! I have not fired the rifle to date, but intend to so in the near future, but not with that load. I also have a modern percussion 8 bore by Hollie Wessel. It is a masterpiece which I will share at a later date on the proper forum. However, I have shot that rifle, which is a tad light at 11 lbs, with 150gr of FF behind a patched ball (no hard card over the powder). Have not chrono'd that load, but fun to shoot. The Krider goes 13lbs with a 30" bbl. The fun continues