Ian-
No, that's not what I meant. I'm 99% sure the "Artillery" Version was the name given to the 1855 model 2-banders (as has been said, also called the "Rifle length" version- just names for the same gun). As others have posted, there probably were others that had barrels browned. I have never seen any with a lock that was browned or case-hardened, though. You could go either way- case in point being the 1841 Mississippi Rifle- which can be found both bright and browned- but the locks are not hardened. You'll see this on 1863 Springfields, Enfields, 1842 rifled muskets, and some others. But not the '55s, so I've seen.
Thanks, and sorry if I confused you, :grin:
-Chris