I purchased what is said to be a Harpers Ferry 1803 percussion conversion w/1819 lock. According to Flayderman's guide, everything matches except it does not have a patch box and the front stock cap is silver, not brass, and of a different shape. It reminds me of the Indian carbine from the Springfield armory, but that doesn't have the silver stock cap. The barrel is 33 3/8", of which the round barrel is 20 1/4". Any ideas? Here are some pictures: