M1919 Browning machine gun


The M1919 Browning is a.30 caliber medium machine gun that was widely used during the 20th century, especially during World War II, the Korean War, and the Vietnam War. The M1919 saw service as a light infantry, coaxial, mounted, aircraft, and anti-aircraft machine gun by the U.S and many other countries.
The M1919 was an air-cooled development of the standard U.S. machine gun of World War I, the John M. Browning-designed water-cooled M1917. The emergence of general-purpose machine guns in the 1950s pushed the M1919 into secondary roles in many cases, especially after the arrival of the M60 in US Army service.
The United States Navy also converted many to 7.62 mm NATO and designated them Mk 21 Mod 0; they were commonly used on riverine craft in the 1960s and 1970s in Vietnam. Many NATO countries also converted their examples to 7.62 mm caliber, and these remained in service well into the 1990s, as well as up to the present day in some countries.

Operation

Loading

The M1919 originally fired the.30 cal M1906 ball cartridge, and later the.30 caliber M2 ball cartridge, contained in a woven cloth belt, feeding from left to right. A metal M1 link was later adopted, forming a "disintegrating" belt.
Loading was accomplished by inserting the pull tab on the ammunition belt from the left side of the gun—either metal links or metal tab on cloth belts—until the feeding pawl at the entrance of the feed way engaged the first round in the belt and held it in place.
The cocking handle was then pulled back with the right hand, palm facing up, and then released. This advanced the first round of the belt in front of the bolt for the extractor/ejector on the bolt to grab the first cartridge.
The cocking handle was then pulled and released a second time. This caused the extractor to remove the first cartridge from the belt and chamber it. As the bolt slid forward into battery, the extractor engaged the next round on the now-advanced belt resting in the feedway, preparing to draw it from the belt in the next firing cycle.
Every time the gun fired a shot, it performed this sequence: the bolt came rearward, extracting the spent round from the chamber and pulling the next round from the belt so that the fresh round ejected the spent one. As the bolt came forward, it chambered the fresh round, advanced the belt, and engaged the following round in preparation for loading. Once the bolt closed, the firing pin dropped, and the round was fired.
The sequence was repeated roughly ten cycles per second until the trigger was released or the ammunition belt was exhausted.
The gun's original design was as a water-cooled machine gun. When it was decided to try to lighten the gun and make it air-cooled, its design as a closed bolt weapon created a potentially dangerous situation.
If the gun was very hot from prolonged firing, the cartridge ready to be fired could be resting in a red-hot barrel, causing the propellant in the cartridge to heat up to the point that it would ignite and fire the cartridge on its own.
With each further shot heating the barrel even more, the gun would continue to fire uncontrollably until the ammunition ran out, since depressing the trigger was not what was causing the gun to fire.
Gunners were taught to cock the gun with the palm facing up, so that in the event of a cook-off, their thumb would not be dislocated by the charging handle, and to seize the ammunition belt and pull to prevent it from feeding, if the gun ever started an uncontrollable cycle of cooking off.
Gunners were trained to manage the barrel heat by firing in controlled bursts of three to five rounds, to delay heating. Most other air-cooled machine gun designs were fired in the same way, even those featuring quick-change barrels, and which fired from an open bolt, two features that make air-cooled machine guns capable of somewhat more sustained fire, both features that the M1919 design lacked.

Firing

When the gun was ready to fire, a round would be in the chamber and the bolt and barrel group would be locked together, with the locking block at the rear of the bolt. When the rear of the trigger was pivoted upwards by the operator, the front of the trigger tipped downward, pulling the sear out of engagement with the spring-loaded firing pin, allowing it to move forward and strike the primer of the cartridge.
As the assembly of bolt, barrel and barrel extension recoiled to the rear of the gun upon firing, the locking block was drawn out of engagement by a cam in the bottom of the gun's receiver. The recoiling barrel extension struck the "accelerator" assembly, a half-moon shaped spring-loaded piece of metal pivoting from the receiver below the bolt and behind the barrel extension. The tips of the accelerator's two curving fingers engaged the bottom of the bolt and caused it to move rapidly to the rear. The extractor-ejector was a mechanism that pivoted over the front of the bolt, with a claw that gripped the base of the next round in the belt. A camming track in the left side of the receiver caused this to move down as the bolt moved back, lowering the next round down on top of the fired case, pushing it straight down out of the extraction grooves of the bolt face through the ejection port. A spring in the feed tray cover pushed the extractor-ejector down onto the next round, so if the feed tray cover was opened, the extractor-ejector would be pulled upwards if the belt needed to be removed.
The belt feed lever was connected to the belt feeding pawl at the front end, had a cam pin at the rear end which ran through a track in the top of the bolt, and a pin in the feed tray cover acted as the pivot between the two ends. The rearward movement of the bolt caused the rear end of the feed lever to pull to the right, causing the feeding pawl at the other end to move left over the belt. The pawl would pull the belt further to the right as the bolt came forward again, also sending the loose M1 link of the previous round to be taken out of the belt to fly out the right side of the receiver. A recoil buffer tube extended from the back of the receiver to make the cycle of the bolt smoother than previous designs, to absorb some of the recoil of the bolt, and formed a place for the pistol grip to be installed.
Except for the M1919A6, all other variants had to be mounted on a tripod or other type of mount to be used effectively. The tripod used by infantry allowed traverse and elevation. To aim the gun along its vertical axis, the adjustment screw needed to be operated. This allowed the point of aim to be moved upwards or downwards, with free traverse to either side, allowing the gunner to set an elevation and sweep a wide band of fire across it by simply moving the gun from side to side. There was no need to control barrel climb or keep careful track of the fall of shots to make sure the fire was falling at the proper range. The gun was aimed using iron sights, a small folding post at the front end of the receiver and a rear aperture sight on a sliding leaf with range graduations from 200 to 1,800 meters in 200 meter increments. When folded down, the aperture formed a notch that could be used to fire the gun immediately without flipping up the leaf. The rear sight also had windage adjustment with a dial on the right side.

Operational use

Infantry organization

As a company support weapon, the M1919 required a five-man crew: the squad leader; the gunner ; the assistant gunner ; two ammunition carriers. The original idea of the M1919 was to allow it to be more easily packed for transport and featured a light barrel and bipod when first introduced as the M1919A1. Unfortunately, it quickly became clear that the gun was too heavy to be easily moved, while at the same time, too light for sustained fire. This led to the M1919A2, which included a heavier barrel and tripod, and could sustain fire for longer periods.

Infantry service

The M1919A4 weighed about, and was ordinarily mounted on a "lightweight", low-slung tripod for infantry use. Fixed vehicle mounts were also employed. It saw wide use in World War II mounted on jeeps, half-tracks, armored cars, tanks, amphibious vehicles, and landing craft. The M1919A4 played a key role in the firepower of the World War II U.S. Army. Each infantry company normally had a weapons platoon in addition to its other organic units. The presence of M1919A4 weapons in the weapons platoon gave company commanders additional automatic fire support at the company level, whether in the assault or on defense.

Vehicle use

The M1919A5 was an adaptation of the M1919A4 with a forward mounting point to allow it to be mounted in tanks and armored cars. This, along with the M37 and the Browning M2 machine gun, was the most common secondary armament during World War II for the Allies. The coaxial M37 variant had the ability to feed from either the left or the right of the weapon and featured an extended charging handle similar to those on the M1919A4E1 and A5. A trial variant fitted with special sighting equipment was designated M37F.

Light machine gun adaptation

Another version of the M1919A4, the M1919A6, was an attempt to make the weapon into a true light machine gun by attaching a bipod, buttstock, carrying handle, and lighter barrel instead of 7 lb ). The M1919A6, with a wooden buttstock, handle, pistol grip and bipod directly mounted to the body of the weapon was in fact one pound heavier than the M1919A4 without its tripod, at 32 lb, though its bipod made for faster deployment and enabled the machine gun team to dispense with one man. The A6 version saw increasing service in the latter days of World War II and was used extensively in the Korean War. While the modifications were intended to make the weapon more useful as a squad light machine gun, it was a stopgap solution. Even though it was reliable, it proved somewhat impractical for its intended role.