Terry, you may well be right about that Lassen Park rifle being "Slotter" rather than Slotterbeck since I never saw it except thru a glass museum case and was probably going by a little card done by some local historian, who might well have been wrong, or him/herself going by a marking partly worn away, or struck at an angle.
I remember looking at that rifle at the end of many shifts and thinking "If I had to rely on a muzzle loader, THAT would be the one." If any ML was ever an "Old Reliable," those big "California" rifles were. There was an "IXL" Bowie there that would have made an excellent backup, too. Brummie's finest. Those old frontier weapons always put me in mind of H.L. Davis' novella "The Kettle of Fire" about NE CA/SE OR in the Indian Wars of the early 1860s.
(Most people never heard of any of this stuff--please DON'T tell anybody about Lassen Volcanic Natl. Park!).