Whoa! With all due respect, and to get this discussion back to reality, there is absolutely no similarity between the Mg17 and the Schwarzlose internals. They are completely different in design, mechanical function and use. The Mg17 design is a very close brother to the Mg15 as noted elsewhere in this thread, with the addition of push through link feed by a roller rather than a magazine. It is an excellent evolution of the MG15.
The Schwarzlose functions with an unlocked breech, the only rifle caliber MG with any success to do so, with beech opening delayed by a toggle that is at a mechanical disadvantage with respect to the axis of the bore. The Schwaezlose functions like the Vickers/Maxim, withdrawing the cartridge from the belt before insertion into the breech.
The MG15/17 are locked breech by means of rotating collar and interrupted threads locking the breech to the bolt during high pressure ignition period. The roller in the MG17 feeds the cartridge by means of a belt identical to the push-through MG34/42 belts, positioning it for chambering. The Mg15 should have been a belt fed, designed like the MG17!!
Again, Musgraves's volume, German Machine Guns has excellent schematics of the internals of the MG17.
FWIW
