Why is there a bolt head on the left side of the barrel? The tang screw is not original. It would be worth having professional cleaning done if the barrel is shootable. It amazes me that so many of this model survived over the years. I have three
Yeah ... I saw that too. And it doesn't line up with "factory". But 1857 was a loooonnng time ago... and lots could have happened to that gun. It went through a war!
Guns back then were all hand made - no assembly line - no perfectly interchangeable parts. They were just "built". By hand - and sometimes with whatever parts were available. By whomever happened to be working at the "factory" at the time. Times of war - the factory most likely had a bunch of different people working and pushed out products the best they could. So standardization probably wasn't great.
Then with field use - who knows what repairs may have been made to it - or any other of it's type, for that matter. So it's probably a little difficult to even decide what was "proper" for the gun - because there were probably many slightly different version of it.
But all that makes it unique - and historic. Those were real people back then - struggling with all sorts of things.
Your musket is an 1816 Springfield that was converted to the Maynard tape priming system in 1857, by Remington. The priming system was not much account and most were converted to use percussion caps, as yours was. The value of the musket has pretty much been destroyed by an amateur cleaning that has removed the patina.