It is reasonable to assume that any Mendenhall Derringer was produced in 1860 or later.
J. HAUSMANN
#242 J. Hausmann was an arms dealer before the Civil War in New Orleans. Little is known about him. Notice that this gun has definite Southern characteristics of some of the Memphis and Nashville guns in the screw plate under the forearm that holds the barrel to the forearm, the fluted nose of the forearm, and the full octagon barrel. All furniture is likewise plain as is characteristic of many of these guns. The grips are bird head shaped and are protected at the butt with a tear drop inlay. There is a screw through the trigger plate holding to the barrel. The caliber is .410.
A friend in Memphis has in his collection an identical gun marked #1 on the tang. Mine is marked #2. I got my gun from Bob Elz of California and the #1 was found in Ohio. Neither of us will sell his gun and we are at a standstill about getting these two identical guns into one collection. No other derringers by this maker are known.
The only markings are on the lock plate itself, hand engraved, as follows:
J. Hausmann
A. J. MILLSPAUGH
A. J. Millspaugh operated in Shreveport, Louisiana. I have never seen one of his guns nor heard of anyone that had one except in one book a mention is made that Philadelphia derringers are known with his name. I do not personally believe he would be any more scarce than a Linde or a Weisgerber.