The Salvator Dormus M1893 was a machine gun of Austro Hungarian origin. It was chambered in the 8x50mm round and designed by Karl Salvator and Ritter von Dormus who first patented it in 1888 and also designed the Salvator Dormus M1896 pistol.
The M1893 was cheaper than the Maxim gun but was gradually replaced by the Schwarzlose MG M.07/12. The M1893 machine guns were mounted aboard the SMS Zenta during the successful defence of the Austro Hungarian Embassy in Peking. Reportedly the guns were remarkably reliable and durable, with one test-firing session running for 9 minutes without a stoppage. The Salvator Dormus was tested by the US military in 1894, although only 600 rounds were available to use so the affair was more of an introduction or familiarization that a true trial. The US report found no direct flaws, but comments that the mechanism did not appear to be sturdy enough for the rigors of field use. Given the Austro Hungarian limitation to ships and fortresses, that was probably a valid assessment.
The Salvator-Dormus was chambered in the 8x50mmR round fed from an overhead magazine and was water cooled with an oil lubrication device. The weapon was unusual the fact it had no trigger, instead it used a pendulum that swung underneath back and forth when released by the operator. The pendulum had an adjustable weight that came with a spring loaded buffer to select the cyclic rate of fire from 180 to 250 rounds per minute. The safety catch was done by hooking up the pendulum to the rear underneath the cocking handle. To cock the weapon was done by twisting the handle half way.
The Salvato-Dormus uses a delayed blowback operation, using mechanical disadvantage of a lever combined with the friction of a fast threaded screw and a heavy spring. When fired, the recoil energy acted on the breech block, which has a shape roughly similar to that of an oversize revolver hammer. A supporting block held the breech block in place against the chamber such that the force of firing would push it out of the way slowly, redirecting most of the recoil energy. The resistance to opening was provided by a carefully engineered lever effect acting on a spring and a fast-threaded screw. Thus in order for the support block to move, the screw had to thread into its housing (which generated friction and slowed down the process) and do so against the force of the recoil spring (further slowing the process). The result was that the breech did not open until the pressure in the bore had dropped to a safe level.
The feed system for the Salvator-Dormus was one of its anachronistic elements, it used a gravity fed single stack hopper. As seen in the photo above, a tall skeletonized feed tower was mounted atop the gun, and an assistant gunner would refill it as the gun was fired. Reportedly clips were made used a spring catch to hold cartridges securely and which fit over the top of the feed tower, which would push the retention spring out of the way and allow the cartridges to drop into the gun’s feed tower. This was a system which would actually turn out to work for the Salvator-Dormus, although it was not suitable to infantry use and would not be adopted by any other military machine gun after this date. One are of foresight in the Salvator-Dormus was its water jacket. Where the Maxim gun and most of its competitors used a simple fill-and-drain water jacket, the Salvator-Dormus was designed for use with a circulating pump. This could allow a constant supply of fresh cold water to keep the guns cool without generating a telltale steam cloud or running dry in extended firing.