Why aren't water-cooled machine guns used anymore?

BigBlueBox

Banned
I'm aware of the increased bulkiness of water-cooled machine guns that makes them unsuitable for squad use. But why are they not used in stationary emplacements or on vehicles anymore? A water-cooled machine gun can fire continuously without overheating far longer than a Gatling gun can, and doesn't require electricity either. So why have they fallen out of favor, while standard heavy machine guns and Gatling guns are still in use?
 
Because Water Cooled weapons are harder to displace. A stationary emplacement in WWI was hard to destroy, either a grenade from up close, an infantry support gun being manhandled over no mans land or a somewhat rare tank, so it could stay put. Now tanks are common, so are IFVs with heavy autocannon, most squads have recoilless rifles/RPGs/rocket launchers and Grenade Launchers, guided weapons exist for aircraft and artillery. Ergo a stationary emplacement will have to displace a lot more now, hence lower weight is more of a requirement

Also post WWI you have the development of quick change barrels, which give most of the same advantages without the bulk or complexity, as well as just better metallurgy making overheating less of an issue, which explains why vehicles don't use them, that and the weight and bulk

Gatling guns are mostly used in situations where rate of fire is the main consideration, not sustained fire, to put as many rounds down range in a limited time as possible. Generally you see them in aircraft, small boat, AA, or CIWS applications
 
It is an interesting question. Water-cooled MGs were used extensively through WWII, but not seen much after that. The US didn't have quick change barrels in WWII (don't really know about modern US MGs). You could change the barrel on a .30 or .50 MG, but certainly not quickly. We still use the venerable Ma Deuce 50 cal, but I've never seen a modern one with water cooling. I suppose, as RamscoopRaider says, that's a matter of bulk and weight, and the lack of a need for really sustained fire in most situations.
 
Water-cooled machine guns were designed to conduct indirect area fire missions. They would be locked down on a tripod and then fired in long bursts for minutes or even hours at a target like a crossroads or bridge several kilometers away. Trying to pull something like that on the modern battlefield would be suicidal, and mortars are better at it anyways. Putting a water-cooled gun on a vehicle makes some sense, but they are very heavy and require a large opening in the armor. A water-cooled .50 AA gun would be enormously difficult to maneuver without a powered mount. Today, nobody wants water leaking all over their electronics.
 

Deleted member 94680

A modern Gatling gun will run out of ammunition before it overheats. Water-cooled systems were a production of necessity rather than for superior performance. Modern GPMGs (does something designed in the 50s count as modern?) can change barrels in seconds.

There’s simply no need for a water-cooled system any more.
 
Water-cooled machine guns were designed to conduct indirect area fire missions. They would be locked down on a tripod and then fired in long bursts for minutes or even hours at a target like a crossroads or bridge several kilometers away. Trying to pull something like that on the modern battlefield would be suicidal, and mortars are better at it anyways. Putting a water-cooled gun on a vehicle makes some sense, but they are very heavy and require a large opening in the armor. A water-cooled .50 AA gun would be enormously difficult to maneuver without a powered mount. Today, nobody wants water leaking all over their electronics.

Sustained Fire and map predicted fire are still used by machine gun platoons in the British Army (and I assume other NATO armies at least). The GPMG has a tripod, specialised sights and other ancils issued to MG Pl for the role.
 
They have been replaced by 20-30mm auto cannons. Each round explodes into many pieces of shrapnel so it’s just as good as firing many bullets one at a time. Plus they can deal with field fortifications and light armor, something rifle caliber machine guns cannot cope with. After all armies don’t send whole battalions charging on foot any more. These weapons are also mounted on vehicles due to the vulnerability and lack of flexibility of stationary fire support. Once fire support is mechanized, what’s the point of a rifle caliber machine gun when heavier weapons can be mounted?
 
I'm aware of the increased bulkiness of water-cooled machine guns that makes them unsuitable for squad use. But why are they not used in stationary emplacements or on vehicles anymore? A water-cooled machine gun can fire continuously without overheating far longer than a Gatling gun can, and doesn't require electricity either. So why have they fallen out of favor, while standard heavy machine guns and Gatling guns are still in use?

Is it possible to use another liquid to improve on the performance of water cooled MG's? Would say mineral oil provide serious improvements?
 
Is it possible to use another liquid to improve on the performance of water cooled MG's? Would say mineral oil provide serious improvements?
Oil has less heat capacity than Glycol, and that has less than Water.

You would need far more of the other fluids for the same heat capacity as H2O

One interesting path that wasn't taken, would have been to use anhydrous Ammonia in a heap pipe setup, as Ammonia has higher heat capacity than Water, and it's a sealed system
 
Well, Naval guns are rapid fire, and **are** water cooled.
I'm guessing that being on a larger weapons platform capable of carrying a few hundred more pounds easily makes it less of an issue. Plus, ships are made to withstand water anyway, so there's less concern of them leaking over sensitive electronics (which are either properly insulated or hardened against water leaks either way).
Oil has less heat capacity than Glycol, and that has less than Water.

You would need far more of the other fluids for the same heat capacity as H2O

One interesting path that wasn't taken, would have been to use anhydrous Ammonia in a heap pipe setup, as Ammonia has higher heat capacity than Water, and it's a sealed system
I'd imagine the problem with leaking ammonia gas once the thing heats up enough was a concern. It would require the gun users to carry gas masks to protect against their own equipment.
 

Deleted member 94680

That might be true for aircraft-mounted weapons, but only due to the ridiculously high rate of fire and low ammunition capacity.

Those are the characteristics of modern Gatling guns. They all have high rates of fire. The ammunition capacity is more limited on aircraft granted, but the idea of a machine gun (Gatling or no) having an unlimited supply of ammo churning through continuously is a movie trope.
 
In your average AFV a water cooled gun would take up way too much space and is hard to design any sort of practical armoured case around (*cough* sentinel *cough*) . In pintle mounts its unpractical compared to your average air cooled MG due to added bulk and not really adding anything practical in return.

Water cooled guns were exceptional in one thing and one thing only, to provide continuous fire at a fixed point from a fixed position and that niche is sorta dead. Considerably more practical designs can do the same just as good while also do a slew of other things.

Gatlings are really only useful on aircraft, AA systems or other systems where rate of fire is crucial. Water cooled guns don't really do anything to replace those. You do not use a gatling if you want sustained fire.
 
The Need for water cooled Machine guns existed when the weapons were relatively rare and tended to be fairly static - although they could be moved around by being rapidly broken down into man portable 'chunks' like a mortar is.

The arrival of reliable LMGs that while could not match the ability to deliver sustained fire could be moved around by a single man or much smaller gun team.

I guess the death nell for Water cooled guns was the development of rapid warfare coupled with the large deployment of MMGs that were nearly as light as LMGs along with the development of Quick change barrels aka the GPMG.

Again while a GPMG cannot match a Water cooled Maxim for shear sustained fire the fact that it and its Ammo and spare barrel can be moved around by 2 men far faster means that a given unit can realistically move them around faster and have more of them.

At the end of the day a Vickers MMG (15 KGs) with Tripod (23 kilos) and an hours supply of water (about 5 liters) weighed about 43 kilo's

A FN MAG with a fixed bipod weighs 12 Kilos - the Tripod weights another 11 Kilos

At the end of the day utility and mobility in the evolving face of increasingly mobile warfare trumped sustained fire.
 
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I'd imagine the problem with leaking ammonia gas once the thing heats up enough was a concern. It would require the gun users to carry gas masks to protect against their own equipment.
That's the nice thing about heatpipe design. no seals to leak

For safety, it's not a lot of gas, far less than than the old GE Monitor Top fridges, that were filled with SO2: and those were in many kitchens till replaced with safer Freon
 
Water-cooled machine guns were designed to conduct indirect area fire missions. They would be locked down on a tripod and then fired in long bursts for minutes or even hours at a target like a crossroads or bridge several kilometers away. Trying to pull something like that on the modern battlefield would be suicidal, and mortars are better at it anyways. Putting a water-cooled gun on a vehicle makes some sense, but they are very heavy and require a large opening in the armor. A water-cooled .50 AA gun would be enormously difficult to maneuver without a powered mount. Today, nobody wants water leaking all over their electronics.

It's more just one method of employment. Water cooled guns were liked because of the way they could could be used for direct fire against enemy troops and they could be fired continuously as long as there was ammo, where they fell down was they were bulky and hard to move forward particularly in an attack over no mans land where even a wheeled carriage was of little use. They were very useful in defensive situations well into WW2 and even Korea, see the impact they had at Glosters Hill where a lot of the Chinese casualties were caused by Vickers guns, indeed the decision of the Glosters to finally withdraw was partially influenced by the lack of water for the Vickers guns, at the end men were using urine to cool the guns.
 
But how many where actually built/bought/designed during WWII and not simply old stock from WWI that where read, available and effectively free?

That is another good point - I imagine that in a total war situation building water cooled Vickers or 1917A1s etc was more expensive than building BESA Machine guns (British copy of the ZB 53) and the 1919A4s (often pressed into service as an LMG due to lack of suitable LMG) at least in terms of man hours per item and use of more modern engineering techniques?
 
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