Mike A., I have one of those California percussion big bore rifles, and have owned a couple of others in the past. All were marked "Slotter & Co" and I think were made in Pennsylvania. All were also marked with a dealer name in San Francisco, like " A J Plate" or some other shop. I think they also all carried a marking about the barrel steel "Warnt...." The Slotter & Co "derringers" carry similar markings.
Michael, I did not know of Henry Jr.s existence until you showed his signature above. Now, that creates a whole new treasurer to look for!
