I'm pretty sure they do. But trapdoors are definitely NOT my forte. Can't keep one (in 45-70) for any length of time. THe various 50-70s and the 1865 model are interesting as transitional weapons from muzzleloading to breechloading, But the 1873 was obsolete when adopted, or close enough. But trapdoor fans won't like me for saying it. Good rifle, but it just shouldn't have been used any length of time.
At any rate, I'm coming up blank on what first used the split swivel for "camping" purposes.
But no surprise, it's been busy!