When I return from the gun show this weekend, I'll post photos of a Hawken rifle made by Joe Corley that belongs to a friend of mine. It is very similar to the third one in the photograph. The top flat of the .54 caliber barrel is unmarked, so its likely not from Art's Shop.
When I removed the barrel, the bottom flat was stamped near the breech, "H & H", ".540", "1*48". About 15" from the breech, "CORLEY" is stamped to the left of a number "12" inside an oval. The number is stamped upside down to the right of the name right side up.
The lock looks similar to what was posted, and I will post photos of it along with the features of the rifle.
Interesting enough, its the first custom-made Hawken I've seen that has color case hardening (faux?) on the buttplate, breech plug (all sides) & tang, entry thimble, nosecap, & escutcheon plates.
Buck