Early in my reenacting career, I used to help with a newsletter, and one of our advertisers was the Ordinance Depot. One of their projects at the time was to reproduce a Hall breechloading carbine. I don't know if the project ever got off the ground but the thought of owning a Hall has never left my mind.
The closest you can come to owning one, is to put one together with parts from The Rifle Shoppe. These guys offer parts for several Hall models.