Q: What's the most difficult prop you had to find for Hell on Wheels?
A: The hardest thing was the Griswold [gun]. There are only 3,600 of them made and the factory was only open for two years before it got destroyed, so trying to find an original one -- you [almost] can't do it... The train, as far as history and the making of it, was a good challenge. From what I've done with Westerns, this was the first chance for me to do anything with the railroad.
Source and more: AMC Blogs
