Previously, we looked at some of the medium machine guns in the US Army’s service. Today we will focus on heavy machine guns. As a practical matter, the US Army has only had one, but we’ll also look at a weapon that has complemented, but by no means replaced that gun.
Near the end of WWI, tanks were becoming common on the battlefield. Not surprisingly, anti-tank weapons began to appear soon after. Of course cannons were popular for engaging tanks, but they had a slow rate of fire, and poor fire control meant they often missed their targets. Coordinating the fires of these cannons with the infantry was difficult as well. Tanks of the day were designed with enough armor to turn rifle and machine gun bullets and shell fragments. Because they had little engine power to spare, armor was kept at a bare minimum. Accordingly, a heavier machine gun bullet could be counted on to penetrate them and would be a light enough weapon to accompany the infantry wherever it went. The high rate of fire would almost guarantee a hit on the tank, with a good likelyhood of destroying or disabling the vehicle. As an added bonus, the heavy machine gun would make an excellent anti-aircraft weapon, a need that was becoming clearer by the day. A heavy machine gun would have greater range than the light machine guns carried by airplanes and the heavier bullet would do correspondingly greater damage to a frail airplane.
Comes again John Moses Browning, a name that anyone with even a passing knowledge of American small-arms knows. Samuel Colt is better known to the public at large, but Browning arguably had a far greater impact. He scaled up his hugely successful M1919 machine gun from the .30-06 rifle cartridge to the .50 BMG cartridge (which he invented as well, specifically for the new gun) and produced the M-2 machine gun.
The aircooled M2 entered service in 1921. It was very quickly adopted to a variety of uses. In it’s tripod mounted form shown above, it was in the weapons company of each infantry battalion. It was also used as a secondary weapon on tanks, an anti-aircraft weapon on trucks (normally one in four trucks would have a mount), mounted on ships and boats, used in either a fixed or flexible mount on aircraft, and later as the primary weapon on armored personnel carriers.
It has been an enormously successful weapon. How successful? It is still in production and is used by at least 34 nations. That number is almost certainly low, and it doesn’t include some nations that we know used the weapon in the past. For instance, the Soviet Union received many guns as part of lend lease during WWII, mounted on trucks, tanks, PT boats, and airplanes. In Iraq and Afghanistan, the M2 is extremely well liked for its long range (up to 1800 meters, or over a mile) and its ability to penetrate masonry walls and cars. When you shoot someone with a .50cal, that tends to be that.
The M2 as seen above can be broken down for carrying into three main components- the barrel, the receiver, and the tripod. Mind you, each of these components is a pretty hefty load all by itself.
My own experience with the .50 dates from my time as a TC on M113s in Germany. I fired the weapon quite a few times on the range, and using blanks, many times on exercises. The .50 was mounted on a pintle attached to a cupola (like a very small turret) on the top of the M113. We had a tripod available if needed, and the barrels were stored in the track. The receiver itself was normally stored in the company arms room. When the time came to load up to roll out of the motor pool to go to the field, I would have to carry all my personal equipment, my rifle, my rucksack, and then I’d have to put the 84 pound receiver on the top of my rucksack and walk a half mile (uphill!) to the motorpool. That was pretty much the toughest thing about going to the field for me.
Still, firing the .50 was a great deal of fun, as it is pretty much the biggest gun in the inventory that you can shoot hands on.
The other heavy machine gun in the inventory is sorta a machine gun and sorta a grenade launcher. The MK19 was developed by the US Navy for use on patrol boats during the Vietnam War. It was further developed by the Army and entered service with the Army soon after that war.
The MK19 fires 40mm grenades at about 375 rounds per minute. It has a maximum effective range of 1500 meters against a small target. The most common 40mm grenade is the HEDP or High Explosive Dual Purpose. This grenade has a small HEAT warhead that can penetrate 2 inches of Rolled Homogeneous Armor and also fragments to kill or wound personnel within a 5 meter radius.
The MK19 is handy in that it gives infantry a means of defeating enemy light armor (and car bombs and trucks) and is an excellent weapon for suppressing enemy machine guns and snipers (would you stick your head up when someone is throwing 375 grenades a minute at you?), and can even penetrate masonry walls.
While the MK19 can be fired from a tripod, operationally it is almost always fired from a vehicle mount. The Army commonly mounts them on Humvees. Typically, the MK19 is found in the weapons company of infantry battalions, used in conjunction with Humvee mounted M2 .50cals. The Marines mount them on Humvees as well. It is also mounted on each Marine Amphibious Assault Vehicle coaxially with a .50 cal machine gun in a small cupola.
There have been several attempts to replace the M2 and MK19 in US service, often by combining their characteristics. To date, none of these attempts have been particularly successful. It looks like the .50cal/MK19 combo will soldier on for some time more.
UPDATE: Here’s another attempt at replacing the M2 .50cal. We’ll see. Read the comments for some of the concerns.
Stay tuned for Part 3 where we examine the Squad Automatic Weapon.