Just playing Call of Duty and noticed the death machine spins and I always wondered why.
In: Engineering
Theoretically you could make a gatling style weapon without spinning barrels, but you’d require a system for loading bullets into each barrel, and firing each barrel. It’d significantly increase the weight to have a separate system for every barrel for no benefit, besides maybe being able to skip a barrel that wasn’t working.
The main problem machine guns in particular need to deal with is heat. You have a small explosion of very hot gasses pushing a hunk of metal down a very tight metal tube and that’s going to create more heat from friction. If you only fire a few shots a minute, the barrel heat isn’t going to be a super big problem, but if you’re firing 800-1000 rounds per minute down the same barrel for long periods of time, then that barrel can get hot enough to actually warp the barrel.
The point of the Gatling gun is that with multiple barrels, you can keep the rounds per minute of a barrel down and give that barrel more time to cool down in between shots. So you can have a ridiculous rate of fire like 3000-6000 rounds per minute while each individual barrel is only truly firing 500-1000 rounds per minute.
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The entire purpose of several barrels is to give the barrels a short amount of time to cool before it is its turn to fire again. This makes it so the weapon can either shoot at a much higher rate of fire and/or for longer periods.
Spinny barrels make better pew, and more pew. More spinny barrels make less heat, so even more pew pew. 😁
TLDR – Single barrel shoot fast, multiple spinning barrel shoot crazy fast (10x faster)
Gating guns and rotary cannons are distinctly different from machine guns
Your [standard machine gun](https://upload.wikimedia.org/wikipedia/commons/thumb/0/07/Browning_M2HB_Normandy.jpg/1280px-Browning_M2HB_Normandy.jpg) has a single barrel, a single breach, and does not spin.
Gatling guns spin so they can pull off stupid high rates of fire. A 6 barreled weapon like the [M134 Minigun](https://en.wikipedia.org/wiki/M134_Minigun) has basically 6 of everything – barrel, breach, and bolt. This duplication means that one barrel can be firing while a couple others are unloading and others are loading the next round and preparing to fire. Instead of having to make one gun that can fire, reload, and fire again extremely quickly ($$$), the duplication allows for each barrel to fire/reload much slower letting things be a bit cheaper and run a lot cooler. The reduced barrel temperature is more important for big guns like [the 20mm M61 Vulcan](https://en.wikipedia.org/wiki/M61_Vulcan) shooting 6000 rounds per minute
There are other spinning weapons like Revolver cannons which have a single barrel but duplicate the breach assembly so one round can be firing while others are loading/unloading. They can’t shoot as fast as a Rotary Cannon but they’re a lot lighter since they don’t have big spinning barrels. They’re less common because standard style completely non-spinning weapons are almost as good and easier to work with.
In the case of the gatling gun it has 5 barrels and one bullet is loaded and fired into each barrel then the spent casing is ejected and a new cartridge is inserted into the barrel and fired. This happnes with each barrell as it rotates and fires
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Machine guns do not spin; gatling guns do.
Bit of history: gatling guns were invented first. There are a couple problems with automatic weapons. The first is that you need to load the round into the barrel, and then you need to eject the spent cartridge. Gatling guns solved that by physically moving the barrel out of the way and having the mechanism tied to the rotation. It’s complicated to describe, but you can see an example in [these](https://i.imgur.com/t2Y75Gc.gif?noredirect) two [gifs](https://i.imgur.com/TmalWdB.gif).
In short, as the barrels are rotated, the cartridge drops down, is pushed into place inside the barrel, the hammer is pulled back, released, and then the cartridge is ejected. Neat! And *relatively* simple. The other problem, though, is that shooting a gun releases a lot of heat into the barrel. By having many barrels, the steel can be allowed to cool a bit between shots. The really neat thing about gatling guns is that you can shoot them as fast as you can rotate them, assuming you don’t melt the barrel. When they were first invented, this meant turning with a hand-crank. This will come up later.
Regardless, they need to rotate because the mechanism is tied to that rotation, and because the spent cartridge would still be in the way of the next cartridge coming in.
Machine guns use the recoil force from the cartridge firing to eject the spent cartridge, cock the hammer back, and load a new round. You can see that action in [this gif](https://thumbs.gfycat.com/HeartfeltImaginaryKiskadee-size_restricted.gif) (although the gun in this gif is *semi-automatic*, meaning the trigger has to be pulled between shots. A fully automatic weapon has a bit of extra mechanism to allow the hammer to release at the right time and fire the round).
Machine guns are mechanically much more complicated, requiring tight springs to shove the rounds back into place, and pretty tight machining to make sure everything fits the way it needs to. It wasn’t long after gatling guns were invented, but it still took a bit of work. Machine guns at the time could fire much faster than gatling guns, since you didn’t have to sit there and crank a thing. They’re also much lighter, since they only have one barrel. Overall, machine guns were mostly better.
And then someone had the terribly efficient idea of attaching a motor to a gatling gun. Why crank it when you can just use a motor? Less work and it’ll turn *way* faster. And then someone was like, motors are big, heavy, and have a max RPM. Why not use an electric motor instead, which will just keep going faster, and is lighter? And with that, modern gatling guns fire a *ridiculous* amount of bullets. You can see in [this video](https://youtu.be/NIJqbKXcSkA?t=280) what looks like a solid line of bullets. In actuality, those are just tracer rounds – bullets with a tiny bit of flammable material so they shine brightly, so you can see where the bullets are going. I don’t know for sure, especially with this gun, but my understanding is that tracers are loaded somewhere between every 7 to 12 rounds. So in the slow-mo of that gun firing, for each bullet you can [almost] see, there’s probably at least 7ish more that you can’t. Fun!
Gatling guns are still much heavier than machine guns, since they still have several barrels, *plus* some kind of motor to drive it. Thus, if you need to shoot a bunch of bullets from something you can carry, it’s almost certainly going to be a machine gun. If you need to empty an entire crate of ammo in under a minute, it’s going to be a gatling gun, almost certainly mounted to something like a vehicle.
1. Shooting out of more barrels can increase the rate of fire. If you just had one barrel, it would be harder to achieve the same fire rate.
2. Heat. When you fire a gun, the barrel heats up. On machine guns, the barrel gets very hot with a continuous rate of fire. Increasing the number of barrels makes the barrels heat up slower since the bullets aren’t always being fired out of the same barrel.
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