US 30 cal machine gun differences

[JohnDillworth]

I guess this question is spurred by the HBO series "The Pacific". The U.S. used 2 types of 30 cal machine guns. An air cooled one, and a water cooled one. So the 30 cal has a water jacket and a hose connected to it. Was there a separate water supply that had to be carried too? Was there some kind of radiator system on the water supply to cool it. Was the circulation caused by the heat difference. How much more longer were the water cooled guns able to fire? What are the major advantages and disadvantages of each type? Did the water cooled ones go away later in the war?
Was the water cooled thing just a British/U.S. invention or dod the axis use it? Was the Mg-34/mg-42 better than either of these?

[Iridium]

ORIGINAL: JohnDillworth

I guess this question is spurred by the HBO series "The Pacific". The U.S. used 2 types of 30 cal machine guns. An air cooled one, and a water cooled one. So the 30 cal has a water jacket and a hose connected to it. Was there a separate water supply that had to be carried too? Was there some kind of radiator system on the water supply to cool it. Was the circulation caused by the heat difference. How much more longer were the water cooled guns able to fire? What are the major advantages and disadvantages of each type? Did the water cooled ones go away later in the war?
Was the water cooled thing just a British/U.S. invention or dod the axis use it? Was the Mg-34/mg-42 better than either of these?

Water circulation was caused the heat difference,both hoses went to a small container of water. One was outgoing and one was incoming. I assume otherwise the only difference was the effect the cooling method had, water cooled having a greater ROF than the air cooled gun. That said, the air cooled gun was probably easily handled by one man while all the accessories needed to get the liquid cooled gun working would probably need two. Not very useful on the offensive.

[AW1Steve]

http://www.rt66.com/~korteng/SmallArms/30calhv.htm
 
Here's a good comparison.
 

[John Lansford]

Yes, the water cooled one had a longer sustained firing time than the air cooled one, but it was also much heavier and took more men to operate.  In long firefights the water could boil away as well, and require refilling in the middle of battle.
 
In the scene where Basilone is at the medic's tent, he's told he had 3rd degree burns on his arms.  Is that possible from water heated to the boiling point?

[jetjockey]

Water-cooled MGs were on the way out by '42-'43. Iridium hit it; water-cooled MG's were bulky, requiring larger crews to move and more TLC. Plus, improvements in metallurgy allowed higher rates-of-fire for air cooled weapons.

The Germans may have had a water-cooled MG, but I can't think of one; the Maxim MG that the Russians used extensively throughout the war may have been originally a German WW I design, but I'm not certain.

The German MG-42 had a slightly larger round, was simple to use/maintain, and had an incredible ROF; you be the judge.

[herwin]

ORIGINAL: Iridium

ORIGINAL: JohnDillworth

I guess this question is spurred by the HBO series "The Pacific". The U.S. used 2 types of 30 cal machine guns. An air cooled one, and a water cooled one. So the 30 cal has a water jacket and a hose connected to it. Was there a separate water supply that had to be carried too? Was there some kind of radiator system on the water supply to cool it. Was the circulation caused by the heat difference. How much more longer were the water cooled guns able to fire? What are the major advantages and disadvantages of each type? Did the water cooled ones go away later in the war?
Was the water cooled thing just a British/U.S. invention or dod the axis use it? Was the Mg-34/mg-42 better than either of these?

Water circulation was caused the heat difference,both hoses went to a small container of water. One was outgoing and one was incoming. I assume otherwise the only difference was the effect the cooling method had, water cooled having a greater ROF than the air cooled gun. That said, the air cooled gun was probably easily handled by one man while all the accessories needed to get the liquid cooled gun working would probably need two. Not very useful on the offensive.

The first really successful machine gun--the Maxim--was water-cooled. An air-cooled MG either had to have a barrel change mechanism or had to limit its RoF to avoid cooking off rounds in the breech. Light air-cooled MGs were first deployed during WWI, and the Germans came up with the first successful air-cooled medium MG in the MG34. MMGs were used to anchor defensive lines and in barrage fire in the offense. Light MGs were used as squad weapons, providing most of the squad firepower. The water for a MMG was either carried, found on the battlefield, or supplied by soldiers. It had to be replenished as it gradually boiled off over time.

[Panther Bait]

The MG-34/42 had a quick and easy barrel change mechanism, allowing the firing rate to be maintained even though it was air-cooled.  Changing a barrel tooks just a few seconds to complete.

[crsutton]

Although both fired the same ammo. The water cooled was really a heavy machine gun and the air cooled a MMG. The lighter MMG was tactically more useful at the cost of accuracy and sustainable firepower. It is always a trade off.

[Whisper]

The M1917 and M1919 fired the same ammo and the receiver group was about the same. The military called the M1917 a HMG because of the sustained rate of fire because of its heat dissiption. There is no magic to machine guns. The faster the bullets go through the barrel, the faster the barrel heats up. You can make a thicker replaceable barrel with ambient heat sinks, like everybody did, or make a thick barrel with a water heat sink, like the M1917 or Vickers. The mechanicals were the same, but the better your heat sink, the more sustained your rate of fire.

[mikemike]

All the really successful machine guns at the begin of WWI were water-cooled. They remained in service until WW2 as HMG's, especially for use in fortifications or fortified positions. The British SAS IIRC used the water-cooled Vickers until the 1970s. Water-cooled MGs were slow-firing, heavy, and unwieldy, but they had one advantage: they could fire continuously for hours which was particularly useful if they were used for flanking fire to protect barbed-wire obstacles or the approach to fortified positions.

I remember reading a book that recounted the experiences of a British infantry regiment in the Korean War. They held a frontline position that was attacked by Chinese troops, and the defensive line was anchored by machine gun positions. The Vickers MGs fired between 50,000 and 80,000 rounds in one night of attacks; essentially, the gunners pulled the triggers when the attacks began (or possibly locked the triggers down) and released them several hours later, when the attacks ended, while the assistant gunners kept attaching ammo belts to keep the ammo feed uninterrupted. In this way the guns established an uninterrupted barrier of bullets in front of the defended position. This was a tactic that had proved itself in the trench warfare of WWI and was, I think, the major cause of casualties there.

[sfbaytf]

This is what i want:

http://www.youtube.com/watch?v=abTGAP7tG0Y

[Mac Linehan]

Gents -

Ian V Hogg states in his book "Machine Guns" (2002) pg 80 that production ofthe M1917 Browning was started in 1917 and that it was still being manufactured in 2002. "The reason for this is that nothing has appeared sufficient of an improvement to replace it".

Quite a complement -

Mac