Thursday, January 24, 2008

850 rounds through an M-60


You may not be familiar with the M60 machine gun. It was almost exclusively a Viet Nam War weapon of the U.S. Military, and while Infantry is known as "The Queen of Battle", the M60 may be considered the "Queen Consort of Battle".

This crew-served weapon was expected expected to lay down a 'base of fire' in any engagement, and it was well designed for that purpose. This belt-fed weapon fired 600 rounds of 7.62 (.308) ammunition per minute. Weighing just (!) 17 pounds, it was capable of laying down what was popularly called 'a wall of steel' (even though it fired copper-jacketed lead bullets, of course) upon the enemy while support troops either maneuvered to engage the enemy from the flanks, or (as a fixed-defense weapon) the support troops engaged the 'leakers' .. those enemy which avoided its deadly kill-zone .. with their M-16 personal weapons.

Much lighter than the M2 .50 Caliber machine gun, this weapon did not require a tripod mounting device to set it up for engagement. The gun was typically carried with the bipod retracted. In the event that the unit found itself in a 'hasty ambush' ... no warning, the unit walked into an ambush and was unable to establish a 'safe' position for the gun ... the M60 could be fired from the hip, as it was usually carried on a combat sling which facilitated its use while the gunner was standing.

Give only a few moments, the gunner could drop to the prone position, deploy the integral bipod support, and provide an immediate 100 rounds of supporting fire. (The bun was carried with a 100-round belt mounted, with the excess belt-length supported by a canvas 'bag'.)

The assistant gunner (AG) carried either 100 or 200 rounds in a linked belt on his person. In a meeting engagement, there was sufficient time for the AG to connect his carry-ammo with the gunner's carry belt so that the machine gun had 300 rounds of 'immediate action' ammunition.

Because this was a major-caliber fun ( .308 compared to the .22* caliber of the M16 carried by most of an infantry company/platoon/squad), this gun was able to pour a solid stream of fire into any enemy ambush position, early establishing a dominating base of fire to overwhelm the enemy's pre-planned ambush.

The only drawback was that after approximately 300 rounds, the barrel would heat up to the point where this air-cooled weapon was unable to further shed excess heat. At that point the screw-in barrel would first turn red-hot ... and the gun would 'cook off' ammunition so that the runner was unable to cease firing without breaking off the belt-fed ammunition.

If this did not happen, the gun would continue to fire to the point at which the barrel would be sufficiently hot that it would turn white, and then discontinue firing because the barrel actually malformed, causing a malfunction in firing.

Changing the barrel (after the approximately 300 rounds) required the gunner to have in his immediately accessible possession an asbestos-based glove with which he could grab the hot barrel, give it a quarter-turn clockwise to disengage it, and discard the hot barrel. A machine gun crew was expected to ALWAYS have a spare replacement barrel. Unfortunately, in the heat of combat (sorry for the pun), the crew didn't always have the presence-of-mind to replace the barrel before the gun locked up. The result is that the gun was often put out-of-service not because it was knocked out by the enemy, but because it was no longer servicable due to heat build-up.

S.A.W.
In the Middle-East (the "Gulf War"), these limitations were deemed unnecessary. While war in Viet Nam, with its predominantly jungle environment required a heavy bullet to penetrate foliage which was being used by the enemy as cover, the essentially desert environment of the Middle East reduced the need for a heavy-bullet machine gun.

Instead of evolving the M60 (7.62mm) to the next generation, the decision was to evolve the M16 (5.56mm). One distinct advantage was that more rounds of ammunition could be carried per pound of load weight, and it wasn't usually necessary to designate an 'assistant gunner' (or 'ammo carrier') for this weapon. Instead of being a crew-served weapon appropriate to platoon-sized or heavier engagements, the SAW was appropriate to squad-size engagements. There was no perceived need to carry a 'brush buster' round; a magazine-fed fully-automatic weapon with a limited initial ammunition supply (~20 rounds) was deemed sufficient unto the tasks for which it was require.

Some of the advantages of this approach were:
  • SAWs require less training than medium or heavy automatic weapons. Fully automatic weapons require large amounts of expensive live-fire training before troops learn to actually hit targets while not wasting ammunition. SAW doctrine reduces training costs by limiting advanced training to a few picked specialists, usually the men who carry the weapon and its spare ammunition.
  • SAWs are more effective than assault rifles in fully automatic mode. Hand-held fully automatic fire is difficult to control and is less likely to hit an incapacitating part of the enemy's anatomy. A SAW usually has a bipod, which permits the operator to rest the weapon on the ground or other object, increasing stability and reducing operator fatigue.
  • SAWs are more reliable than assault rifles under intense firing. A practical assault rifle needs to be lightweight, and is therefore prone to overheat or malfunction under the stresses of continuous fully automatic fire. Because it is carried by a specialist with a specialized pack load, a SAW can have a heavier barrel and a sturdier action without unduly burdening the entire squad.
This was 'good theory', but in practice the advent of Urban Warfare again showed that heavy bullets provided the penetration needed for effective assault-type warfare. Also, the ability to fire a HUGE number of rounds spoke in favor of an M60-type light machine gun ... except for the niggling problem of rapid overheating.

Enter the improved metallurgy of the 21st Century M60 machine gun.

This gun is able to fire 850+ rounds of ammunition in a very short time, without the need to change the barrel. The overall design hasn't changed significantly since 1960, because it is now able to meet a newly defined mission statement:

"Put a lot of heavy rounds downrange, quickly, without a debilitating maintenance overhead."

The new version of the M60 machinegun performs so well that it meets that minimal requirement handsomely. Yes, it IS a 'crew-served' weapon, if only because the gun cannot be uses to its maximum potential without an assistant-gunner to feed the weapon to the limit of its capabilities. It's still a 17-pound weapon, and carrying the gun with a 'ready action' ammunition in excess of 100 rounds is still a debilitating burden on the gunner.

But with an assistant gunner whose only duties are the (a) feed the gun, and (b) protect the gunner, this new-and-improved light machinegun seems likely to meet mission requirements which have yet to be fully defined in a combat environment.


One thing is sure: the new and improved M60 can not only lay down a daunting 'base of fire', but it can hold its position for a significant period of time, but it can dominate the battleground during that period.


Fifteen THOUSAND rounds? Woof!
(DOWNLOAD this 3mb file here.)

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