This is a 44 caliber Philadelphia Deringer by Henry Schlotterbeck. H. Schlotterbeck was an employee of Henry Deringer in the 1850s and when he left, promptly opened a shop and made copies and selling them as Deringer pistols. The barrels are marked wart steel and J. Deringer / Philadelphia and has a 44 caliber 2 ¾’ barrel and lock were marked J. Deringer. The mechanical function is very good and the bore and wood is very good. These were a direct copy infringement.