I find these black powdah arms fascinating, so many “1sts” ... 1st breechloader issued to a standing army, 1st rifle with a receiver, 1st ambidextrous use firearm, and 1st item truly manufactured with interchangeable parts. Eli Whitney got the credit, but parts within his cotton gin would only interchange within those of the same production run. John Hall is also credited with inventing the micrometer, horizontal milling machines, and the modern thread forms we still use today. A bolt purchased today would fit one of his rifles made in 1819. In fact, the 1st 100 rifles he submitted for the military acceptance trials passed, then were taken apart and put into separate piles of same pieces. Assemblers - not gunsmiths - then took a part from each pile randomly and re-assembled all 100 rifles ... and they too all passed the acceptance and firing tests! I have 2 originals, 1 each in flintlock and percussion ignition, each as issued. And fireable, as they are a hoot to shoot! Just look at that bore on the flint model ... still looks NEW! The clearances between the breechface & breechblock is just a few thousands of an inch.