B
Bullethead
Guest
Logic Says: there are 2 kinds of jams.
MECHANICAL . . Bit of a problem with your interrupter gear linkage, some High G manuvers might clear it - might not
HEAT . . From too long a burst - - kiss the baby
Then again it might not be the guns at all - -Feed problem - - Bent bullet - - it is 1917 afterall. - -again - kiss the baby
In my experience with real MGs, you can divide malfunctions into 2 main categories: mechanical and ammo-related. Only the ammo-related things are really jams; the mechanical issues mean some part(s) of the gun itself or its supporting mechanisms (mounts, feed trays, synchronizer/interrupter, etc.) are physically broken, either from wear and tear or enemy action.
The mechanical problems are pretty much impossible to fix for troops in the field or in flight. They just don't carry spare parts and the tools sometimes necessary to install them. I'm talking about springs, extractors, etc., not spare barrels. Pilots are even less likely to be able to do anything here because of the difficulty in even reaching the relevant part of the weapon, let alone fixing it.
Ammo problems come in 3 flavors: failures to feed, failures to fire, and failures to extract. Failures to fee and failures to extract are your real "jams", because they involve rounds not moving properly through the system. All of these can be symptoms of underlying mechanical problems, or can be the fault of the ammo or belt themselves.
Depending on exactly what went wrong and how badly, both pilots and ground troops might be able to fix ammo problems in more or less time. This assumes, of course, that the gun itself isn't broken somewhere. What you do here is called "immediate action" these days. Mostly, it consists of manually operating the bolt, to try to get the gun's mechanisms to move the problem ammo through and out. IIRC, all WW1 planes with Maxim/Spandau/Browning guns had a way for pilots to do this, either by pulling the regular ground charging handle or a cable attached to it. You can also open the breech and re-insert/re-align the belt, and/or pull out and discard rounds that might be in the wrong place, or bent, or whatever. Depending on where the gun was mounted in relation to the cockpit, this could be rather difficult for pilots, however.
The above works best on failures to fire, which (again assuming a physically sound weapon) are usually due to dud rounds. It will also work on failures to feed, provided no round got so badly cross-threaded as to totally wedge the gun's parts into place. It will SOMETIMES work on failures to extract, provided there's something for the extractor left to grab onto. Unfortunately, most failures to extract are due to the cartridge case coming apart (provided, again, that the extractor hasn't broken), either just the part of the rim where the extractor touches, or the whole head of the case coming off. These problems would be next to impossible to fix in the air, because they usually require inserting the clearing rod in from the muzzle to knock the bad case out of the chamber.
Besides ruining the barrel, the heat build-up from firing long bursts can cause thermal expansion of the gun mechanism. All the moving parts in there have fairly tight tolerances so when they change size and/or shape, they don't work properly. This can be the underlying cause of failures to feed and extract. Prolonged heating can also cause parts of the gun to break under the stress of firing (they get slammed around pretty hard as it is).