One of the early potential competitors to the Maxim gun was the Austro-Hungarian Salvator-Dormus machine gun. Designed by Austrians Grand Duke Karl Salvator and Colonel von Dormus, is was first patented in 1888, although it has come to be known as the model 1893 because this was when the Austro-Hungarian Navy adopted it. Also known as the Skoda machine gun (by virtue of being manufactured by the Skoda works), the design is an interesting mix of both obsolete and forward-looking elements.
At a basic mechanical level, the Salvator-Dormus is a delayed blowback action, using mechanical disadvantage of a lever combined with the friction of a fast-threaded screw and a heavy spring. It was chambered for the 8x50R cartridge, which was a smokeless-powder modern cartridge used at the time in the Austrian infantry rifles – so this is a true full power cartridge (244gr / 16g round nose bullet moving at about 2,000 fps / 610 mps).
When fired, the recoil energy acted on the breechface, which has a shape roughly similar to that of an oversize revolver hammer. A supporting block held the breechface 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. This cutaway example makes the system much clearer:
A couple additional elements to describe are the pendulum below the action, and the handle at the back of the recoil spring. The handle is simple; that is used to manually charge the action, as there is no other lever allowing manipulation of the internal parts. The pendulum is a bit more complex and certainly less common – it is used to adjust the rate of fire. That weighed pendulum swings back and forth with the action as each shot is fired, and as the weight is made heavier and/or mounted lower on the stalk, the amount of inertia in the pendulum increases, thus retarding the rate of fire. That was its purpose; to allow the rate of fire to be adjusted manually. The cutaway is a bit misleading in this regard, as it shows the pendulum in the breech-fully-open position, while the breech is actually closed.
Using this mechanism, the rate of fire could be set as low as 175 rpm and as high as 500 rpm (according to US military trials of 1894, as quoted by Chinn).
The feed system for the Salvator-Dormus was one of its anachronistic elements – it used a gravity-feed 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.
The gun was formally adopted by the Austro-Hungarian Empire, but used for naval and fortification defense and not infantry service (which makes sense, given its design limitations). At least one of the guns did see combat, as they were mounted on the Austro-Hungarian battle cruiser Zenta when it was deployed to Peking during the Boxer Rebellion. Reportedly the guns were remarkably reliable and durable, with one test-firing session running for 9 minutes without a stoppage. That may not be Maxim-level reliability, but it is still quite good for the era.
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.
One of our readers, Ed S., thoughtfully supplied a bunch of photographs of the two Salvator-Dormus machine guns currently on display at the Museum of Military History in Vienna, which I have included below. Thanks, Ed! One element I have not figured out yet is the purpose of the hooked vertical lever standing above the pendulum on this particular gun – it does not appear in any other pictures I have found, and I am not sure what its purpose it. I also have not identified the actual trigger of the gun, for what that’s worth.
This second example appears to be a prototype – I don’t have any specific detail on it.