Flintlock era rifle ID help

[DaveM]

This rifle is a bit rough but interesting and evidently heavily worn and used for a long time.  I believe this was originally a flintlock - it has the two bolts, and the wood is notched at the top of the lock for the cock and there is a dent area where the cock would have struck.  Seems to have some type of barrel markings very faint, with what seems to be some squiggle lines faint on the barrel.  Also has squiggle decoration on the hardware.  Also a stamped "JS Baker" in small letters on the barrel but bold (unlike the squiggles on the barrel).  Not sure if Baker converted / shortened it, or made it - because it doesn't strike me as a Philadelphia style gun at least of a type I've seen.  I learned that a JS Baker was first listed in Philadelphia as a gunsmith in 1818, and not in any of the Philadelphia city directories prior.  He died in 1836 (born 1761).  Have no idea where he was working before moving to Philadelphia in 1818 - or if he even made the gun or just modified it.  The barrel and forestock were shortened at some point at the muzzle - based on the shifted barrel lug it was shortened on this stock so I believe this is the original stock.  No evidence of a restock that I could find and the buttplate tang is very worn and beveled like the triggerguard.  It is about 50 cal. full octagon and very heavy. It must have been extremely heavy as full length.   The patchbox release looks like it originally was a type of switch that came through the cheek piece side and is now broken. Any thoughts on origins or time period appreciated thanks!