The Henrion, Dassy and Heuschen revolver, or HDH revolver, is a double-barreled Franco-Belgian revolver.
The revolver was produced from 1911 to 1928 by the Henrion, Dassy and Heuschen company, otherwise known as HDH. The revolver was usually marketed under a name denoting power and masculinity, such as "Wild West", "Terrible", "Redoubtable" and even "Machine gun HDH".
The revolver has two barrels, but only fires one shot at a time due to staggered chambers in the cylinder. The revolver has a single hammer with two firing pins. Reloading required the breaking of a hinge along the top-rear of the weapon's frame.
The Ludovici revolver is a derivative of the HDH revolver.