The Maxim heavy machine gun is the world's first truly successful automatic weapon powered by gunpowder gas. It is called the Saidian gun in China. The gun was invented by British Hiram Stevens Maxim in 1883, and the principle test was carried out. It was patented in 1884.
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The Maxim heavy machine gun has a caliber of 11.43 mm and a weight of 27.2 kg. It adopts a short-recoil (19 mm) automatic mode and a water-cooled barrel. It uses a 6.4-meter-long canvas belt with a capacity of 333 rounds. The belt can be connected. The theoretical rate of fire is 600 rounds/minute. It can be fired in single or continuous shots. It can also be adjusted to a slow rate of fire of 100 rounds/minute through the rate of fire regulator.
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Due to the burning of propellant, the maximum temperature in the barrel of a heavy machine gun can reach 3000℃ when it is fired continuously. Under the repeated flushing of high-temperature gas and the friction of the bullet passing through the rifling, the temperature of the barrel will rise rapidly. If there is no cooling device, the barrel caliber will become larger and the air tightness will decrease after firing more than 200 rounds continuously, and the projectile will be closer. The nutation of the bullet passing through the barrel will become larger (the bullet bounces and collides in the barrel with a larger diameter and flies out), resulting in a larger dispersion. If the firing continues to reach 400-500 rounds, the barrel temperature will be higher, and it will begin to turn red and soften. The bullet passing through the rifling part will cause permanent damage to the inner wall of the barrel. If the firing is still not stopped, the barrel will be deformed and scrapped, and even serious accidents such as explosion will occur.
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Structural line diagram of Maxim heavy machine gun
In this regard, the Maxim heavy machine gun adopts the method of using a water-cooled sleeve. There is a closed metal sleeve on the barrel of the Maxim heavy machine gun. The sleeve was originally made of brass, and later steel was used. Water was filled in the sleeve and used as a coolant to cool the barrel. We all know that the boiling point of water is 100℃. As long as the water in the sleeve is not boiled dry, the temperature of the barrel will not exceed 100℃. Because this design is very practical, in addition to the Maxim heavy machine gun, the heavy machine guns of the same period such as the American Browning M1917, the Italian Fiat-Levi M1914, and the Austrian Suwasloser mostly used similar water-cooled sleeves.
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Many military fans have discovered that there is a small round iron sheet in front of the water-cooling sleeve of the barrel of the German Maxim machine gun and at the rear of the trumpet-shaped muzzle device. What is this for?
Many people believe that this small round iron sheet can be used to block bullets. The reason is that the Maxim machine gun uses water cooling, and the huge water cooling jacket is made of thin copper plates, which has poor bulletproof ability. On the battlefield, once the machine gun water cooling jacket is penetrated by bullets or shrapnel, the cooling water will quickly drain and the machine gun will not be able to fire normally.
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In fact, the correct name of this iron sheet is called "flame arrester", which is to prevent the bright flame of gunpowder gas from the booster at the front end of the barrel during night battles, exposing the position of the machine gun.
The Maxim machine gun adopts a tube-recoil automatic principle. The barrel is floating. After the bullet is fired, the recoil drives the barrel to recoil. The barrel and the bolt are buckled together. Under the pull of the recoil, the shell is pulled out and thrown out, and then the bullet is pushed into the chamber and fired again. The series of actions completes the automatic cycle. In order to increase the recoil and increase the rate of fire, the Maxim machine gun is equipped with a gunpowder gas booster at the front of the barrel, using the gunpowder gas ejected from the barrel to expand in the working chamber to accelerate the barrel retreat.
Therefore, the muzzle of the Maxim gun is composed of two parts, one is the barrel that can recoil, and the other is the horn-shaped flash suppressor at the front of the barrel. In the middle is a cavity sleeve, which is a device like a hexagonal nut behind the round iron sheet. This is the gas booster, and there are 6 gas discharge ports on the hexagonal nut.
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When the Maxim machine gun is fired, after the bullet leaves the barrel, the gas from the burning and expanding propellant of the bullet will enter the recoil expansion cavity of the barrel as the bullet leaves the chamber, which is the gas booster of the cavity sleeve. Here, under the action of the gunpowder gas pressure, the barrel will be accelerated to move backward. With this gas booster, the recoil speed of the barrel can be increased, the firing rate can be increased, and the sustained firing rate of the Maxim machine gun can reach 600 rounds/minute, that is, 10 rounds per second.
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The gunpowder gas that has completed the expansion and work in the cavity sleeve booster can be discharged through a 6-hole discharge port. However, the temperature of the gunpowder gas is still very high at this time, and there are residual burning gunpowder particles, which form bright flames discharged laterally at night, which can easily expose the target. Therefore, the Maxim machine gun installed a small round iron sheet at the front end of the gas booster to block the flames discharged laterally.
What about the brighter muzzle flames ejected from the muzzle of the Maxim machine gun? This problem is solved by a trumpet-shaped muzzle flash suppressor, which can suppress part of the muzzle flame and reduce the intensity of the muzzle flame flash when the machine gun is fired.
On the battlefield, the machine gunner is the most important target of the enemy sniper. Although it is just a small round piece, it can greatly improve the safety of the machine gunner. After the First World War, countries have realized the power of heavy machine guns and began to develop and equip various types of machine guns. The design of machine guns has become more and more humane, no longer as bulky as the Maxim machine gun, and the performance has been greatly improved, and the round iron sheet (flame blocker) at the muzzle has disappeared.
