[Buffalochip]

I think it was definately a flintlock at one time. There is a notch in the wood just above the lock which is there for clearance of either a percussion hammer or flintlock "cock." Since notches for a percussion hammer usually go all the way back to where the hammer would be on full cock, this notch must be clearance of the lower jaw of the cock, which means flintlock.

The box is a patch box, but it could be used for caps, cleaning jag, etc. From time to time you will find patch boxes on percussion rifles--sometime they were converted flintlocks, sometimes they were transitional pieces, sometimes it was just some backwoods gunmaker's preference. However, I suspect very few flintlocks would have cap boxes. (i'd say "never have cap boxes," but I'm sure there is one out there somewhere).