1874...

That looks like a hand scraped finish on that barrel. I say this because I worked for a major American machine tool builder for 29 years and their tool room lathes had hand scraped beds. It was a tedious job but the guys who did it were very good at it, and it supposedly produces a flatter and truer surface than grinding. That's why they they did it on their tool room lathes.

That said... back in the late 70's, a guy I worked with built a T/C Hawken rifle from a kit. He took the barrel in and had the guy who had been scraping for 35 years scrape finish his barrel before he had it blued. Needless to say, it was one of the most unique barrels I'd ever seen on a muzzleloading rifle until now.

BPS