AHC: Delay the development of the machine gun enough that Gatling guns would still be used in WW1

My first thought was that you'd need to delay the development of smokeless powder (really less smokey powders), in all of its various forms, to keep hand-cranked machine guns prominent. However, even that might not be enough as a minor bit of research seems to indicate that the Maxim gun was originally designed and operated with black powder. The gun worked just fine, but the amount of smoke generated was truly immense, causing the developers to look into the results of other experiments on smokelss powder. However, if there weren't parallel efforts to develop smokeless powder going on, the volume of smoke might be accepted as a worthwhile drawback of the huge firepower offerred by truly automatic weapons. So, I don't think delaying smokeless powder would be enough on its own? Perhaps something to do with metallurgy? I'm not knowledgable enough on that to really offer an opinion though.

If we do find a way to make cranked weapons like the Gatling, Nordenfelt, etc. relevant for longer, I think we're likely to see adoption of methods to increase the weapons' rate of fire. IOTL, in the 1890's IIRC, Gatling succcessfully experimented with using an electric motor to drive the crank of a Gatling gun, and achieved truly astonishing rates of fire. If there are no other truly automatic machine guns around, it seems likely that system would be adopted.
 
As Captain Jack mentioned, Gatling did motorize his gun. Rather than keeping the normal machine gun from being developed, perhaps the motorized Gatling gun gets improved as well. Useless in the trenches due to the need for a power supply, it could still have some significant uses. As a fortification gun, it would be without peer. It would be a fearsome AA gun, especially in the larger calibers. Carry a pair aloft in an airship, and the sheer amount of lead could keep enemy fighters from becoming as much of a problem.

Mount it on ships, or on the first tanks and armored cars, and it'd be murder on infantry.
 
As Captain Jack mentioned, Gatling did motorize his gun. Rather than keeping the normal machine gun from being developed, perhaps the motorized Gatling gun gets improved as well. Useless in the trenches due to the need for a power supply, it could still have some significant uses. As a fortification gun, it would be without peer. It would be a fearsome AA gun, especially in the larger calibers. Carry a pair aloft in an airship, and the sheer amount of lead could keep enemy fighters from becoming as much of a problem.

Mount it on ships, or on the first tanks and armored cars, and it'd be murder on infantry.
Indeed. Those ideas have come up before on the one or two occassions this has been discussed. Really, the uses of a motorized Gatling gun are so obvious I'm frankly surprised it wasn't pursued IOTL. I mean, sure there are drawbacks, but I find it hard tp believe it wouldn't have been useful in some niche.

As you say, it would be an horrendously effective weapon in fortifications, on ships, and later mounted on vehicles. I'd expect it to be used anywhere a high volume of fire was desired, and it was possible to carry the power supply and vast quantities of ammunition. I hadn't thought of the weapon's use as a AA gun, or mounted to airships - both are good ideas. Personally, I'm not sure it would do very well as an airship weapon because of the sheer amunition consumption limiting its effectiveness. As an AA gun it might well be excellent, at least for defending important fixed points. Imagine a fortress or warship with even half a dozen weapons mounted in an AA capacity. That's a lot of lead being thrown at hostile aircraft. However, if we take the route of delaying smokeless powder all of those roles are going to be diminished, though not eliminated, by the huge amounts of smoke produced by even short bursts.

One development I see coming fairly quickly is the adaptation of Gatling's motorized system to the Hotchkiss Revolving Canon, or a similar weapon. Rate of fire of a machine gun, firepower of a a light artillery piece. Absolutely devastating as an anti-torpedo boat weapon and useful in sieges too I would imagine.

There are lots potential impacts of this, too. It could well change naval and infantry doctrine in the late-1800's. If it leads to more effective anti-torpedo boat armament on warships, that will weaken the Jeune Ecole school of naval thought and possible change nations' fleet dispositions. Similarly, fortresses may be harder to crack.
 
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