Note: This material is from the original Geocities Tour of Duty Advisor's website.
The primary American infantry rifle used in Vietnam was the M-16. This fired a 5.56 mm (.223 inch) bullet. The rifle is fired by inserting a loaded magazine (a reloadable metal box that holds the cartridges) into the bottom of the rifle, and making sure it is locked in place. Then the bolt has to be pulled back, which is done by pulling a T-handle to the rear and letting it go. This loads the first cartridge into the weapon. The two procedures together are called "lock and load."
On the left side of the receiver (the receiver is the back part of the weapon, with the operating parts), there is a lever with three positions: SAFE, SEMI and AUTO. The rifle will not fire while this lever is on SAFE. Turning it to SEMI puts it on semi-automatic. Semi-auto means "self-loading". You fire a round (a "round" is one cartridge) and the weapon reloads itself for the next shot. But you have to pull the trigger again to fire. The last position is AUTO. Automatic ("full-auto" or "rock and roll") here means that, as long as there is ammunition in the weapon and the trigger is held back, the weapon will fire by itself until it is empty. Troops practiced flipping the lever from SAFE to "rock and roll" in one quick motion. But full automatic fire with any rifle is inaccurate and usually a waste of ammunition. Your first few rounds might hit the target, but the majority would be high and your magazine will be empty in 3-4 seconds.
The M-16 was designed by the Armalite Corporation and called by that name, even after Armalite was acquired by Colt Firearms Inc. It had a very unusual appearance when it was introduced, making use of lightweight metals and high tech plastics. Some GIs called it the "Mattel rifle" after a toy company of that name.
The M-16 acquired a bad reputation, early on, for jamming in combat. Many soldiers were suspicious of them. The rifle was hurried into service for Vietnam and there were consequently a number of problems with it. The first was the magazine. The rifle held its ammunition in 20-round detachable magazines. Due to a design defect, if you actually loaded 20 cartridges into it, it would usually jam. It worked just fine with 17-18. That was one of the things you were told in-country by your unit. Soldier knowledge. JUST load eighteen rounds.
The second problem had to do with cleaning. Most military rifles are pretty forgiving of maintenance. Run a cleaning rod down the barrel and put some oil on their working parts and they work fine. The M-16 isn't like that. It has small, close-fitting parts, that need to be kept clean and brushed off of all dirt and powder residue. This was not generally understood at the time. A toothbrush was eventually issued for cleaning. Until then, GIs just purchased an extra one for their rifles.
If you took care of those two things, the rifle would work fine.
M-16 ammunition was issued in several ways. It could come either in cardboard boxes of 20 rounds each, or in cotton disposable bandoliers. Each bandolier came with 140 rounds, in stripper clips, in seven pockets. In either case, the rounds had to be loaded into magazines, a tedious task. Smart troopers nevertheless periodically rotated (or shot up) old ammunition, disassembled and thoroughly cleaned their magazines when they could.
The CAR-15 (XM-177) rifle was the "carbine" (shortened) version of the M-16, also made by Colt-Armalite. The barrel was shorter and the stock telescoped, so the whole weapon was shorter overall. The CAR-15 had its own development problems as well as sharing those of the M-16. Early versions were especially unreliable. Eventually the problems were corrected , but two remained, intrinsic to the design, and its shorter barrel. The rifle had a very large muzzle flash, a handicap when shooting at night. And it was a much louder weapon to shoot.
The rifle was issued to two very different groups of users. The intended recipients were the Army's elite Special Forces, especially MACV/SOG, and the LRRP (Long Range Reconnaissance Patrol) teams. However, because of its short, handy size, it was often appropriated by high-ranking rear-echelon staff officers. Every general's aide in Vietnam managed to get himself one too. It used the same magazines as the M-16, with the same restrictions (JUST 18), but also came with the first 30-round magazines that later became the standard for both. You could put 30 rounds in the magazine, but 28 would be best. By the way, the 5.56 round has nothing to do with the little .22 caliber bullets teens learn to shoot in summer camp.
The standard US machine gun in Vietnam was the M-60. It was used by ground troops, in vehicles and on helicopters. It fired the 7.62mm NATO cartridge from a disintegrating 50-round belt. Disintegrating means that the 50 round belt included 50 separate metal links, each of which held one cartridge to the next.
The weapon was used like this: to load it, you first flipped a lever at the back of the receiver and the top flipped up. You then carefully positioned the belt, links up, and closed the cover. Then you pulled the bolt handle to the rear, applied the safety (a lever within easy reach of your left thumb) and you were ready. Flipping off the safety and pulling the trigger fired the weapon.
When the belt fed into the gun, the links were stripped off and tossed. One belt could easily be connected to another; in theory, indefinitely. However machine guns RAPIDLY get hot in use and finally the barrel will melt.
The M-60 dealt with this problem in two ways. First, the barrel was detachable by a quick-release lever, and the gunner or his assistant carried a spare. Second, the barrel was made of a VERY tough steel. It could be fired until it turned, first, red-hot, then orange, then white, then transparent, where you could actually see the individual bullets going down the barrel. At that point, however, you had BETTER change the barrel or it would melt. (A helmetfull of water would accomplish the same result, but nobody usually had that much water to spare, unless there was a stream or a rice paddy nearby.) However, if removed even at that point, and thrown aside, the barrel would cool and later be as good as new. Gunners were, in any case, taught to fire short bursts.
There were some problems with the M-60 as used in Vietnam. The weapon was heavy at 23 pounds and ackward to fire unless prone, or from the hip. The belts weighed about ten pounds each. There was no way to carry it with a full belt in place. Gunners on the march usually inserted a short belt of only ten or twenty rounds. If there was time, you could put in a full belt, but in the meantime, you had SOMETHING to shoot immediately. The trouble with carrying the weapon like this was this was that the loose belt clanged against the side of the receiver as you walked.
The other problem with belts was that they exposed the links and ammunition to dirt, water and grime, not conducive to optimum performance. Slung across the chest, as most gunners carried them, the ammo belts reflected light. In fairness, the military had not intended them to be carried like that. They were supposed to be carried in metal cans. But the cans were more useless weight....so...
And speaking of belts, as they came from the cans, every fifth round was a tracer. The belts had to be broken down and the tracers pulled. (Remember Murphy's Law #27: "Tracers work both ways.") If there wasn't time, like on a nightime resupply, well...OUR tracers are RED, the ENEMY's are GREEN. Soldier's knowledge! Remember it!
M-60 machine gun in use as a helicopter door gun. Note empty C-ration can
There were so other problems too, with the "Sixty." The gun really required an assistant gunner, to manipulate the belt and "feed" it to the gun at the right angle. This was overcome in aircraft and vehicle guns by brazing an empty C-ration can to the side of the receiver. This brought the belt to the correct angle the gun liked.
There also wasn't a real good way, with the early M-60s, to get a hot barrel off once you unfastened it. The gunner was supposed to have an asbestos mitt, but nobody I knew ever saw one of those. (They are all probably under lock and key somewhere now, waiting the outcome of an OSHA court case.) People just usually took their sweatrags off and PULLED. Gunners and assistant gunners sometimes suffered severe burns, changing hot barrels with their bare hands. (You don't notice stuff like this in combat. Only after.)
Finally, the weapon was not entirely "soldier-proof" and required a well-trained operator. It was possible to assemble some of the parts incorrectly, and everything would appear to be fine. Except it wouldn't go "bang." It would then have to be disassembled to see why, which is inconvenient in combat.
For all that, the M-60 was considered a powerful and reliable weapon in the field. Its heavy bullets would penetrate brush, chop down small trees and demolish a cinderblock wall in a few seconds. But remember, fire short bursts! Soldier knowledge.
After hearing about the M-16 and the M-60, everyone will be happy to hear about the M-79 Grenade Launcher. The GIs were, too. It was a VERY simple and effective weapon. It fired a single 40mm projectile. A latch on top broke it open like a shotgun for loading.
It had flip-up sights, but an experienced operator didn't really need them. With some practice, you could learn to fire a round into something the size of a trash can at 150 yards. You broke open the weapon, inserted a round and fired. (There was a safety lever ahead of the trigger.) The weapon had a mild recoil.
It could fire a variety of rounds, including small flares. But the two most common were a high explosive and an anti-personnel round. The anti-personnel round was unique in that it fired a cluster of tiny darts, called flechettes. Their codename was "Beehive," and that was what the anti-personnel round was called.
All rounds had to travel a short distance (actually they had to make a certain number of revolutions) before the grenade's impact fuse would arm. This distance depended on several factors, but was a minimum of about 50 feet. Below that distance, you are just throwing something at the enemy. The impact might knock him down, but the round wouldn't explode.
Officers, machine gunners and medics were also issued a pistol. Its correct designation was M1911A1, the year it was adopted, but everyone just called it a "forty-five automatic" or "forty-five." In this case "automatic" means "self-loading," NOT that it would fire continually if the trigger was held back. It fired seven .45 caliber bullets from a detachable clip. It had been the standard US military pistol since before WW I and was considered a proven "man-stopper." US doctrine holds that a pistol is a last-ditch weapon and troops received only rudimentary training in its use. No one was very confident about hitting anything with it, but you knew if you did, it would do the job. It was a tough weapon too, and could survive all kinds of abuse. One disadvantage was that it required two hands to load the first round. It could not be carried safely "ready to fire." (If it was dropped on a hard surface, it could go off.)
The .38 revolver was another kind of pistol issued to aircrews as a survival weapon. They could also take a .45 automatic if they wished, but everyone in the crew usually had to agree to carry the same weapon, so they could share ammunition if they were shot down. Although much less powerful than the .45 automatic, the .38 had a number of advantages. It was lighter, safe to carry loaded and ready to fire, totally reliable, required only one hand to shoot, and, if dropped in water, was self draining. It was also the standard weapon of virtually all American police departments, so it also had proven effectiveness. As a disadvantage, it was carried with only five rounds.
The M72 LAW (Light Anti-tank Weapon) was a disposable launcher for an anti-tank rocket. It should have been very effective, but it wasn't. The problem wasn't the weapon, but the way it was used. It held its anti-tank rocket inside a collapsible, telescoping tube. It was intended to be carried like that, collapsed, until needed, but many GIs tried to carry the weapon "ready to fire." There were some external covering caps that had to be unhooked at each end to shoot it. Then you opened it up. Once you did, however, all sorts of moisture got into the launcher. If you carried it around like that for a day or so, or even if you opened it up, carried it, and then closed it again, it mostly wouldn't fire. It quickly got a reputation as a "dud" weapon.
US soldiers carried several kinds of hand grenades. They all worked the same way. The most common was the M-26 fragmentation grenade, called a "frag."
As most of you know, the grenade works as follows. While holding the lever firmly to the grenade's body, you pull the safety pin free, using the attached ring. The lever is now retained only by the pressure of your hand against the tension of the spring-loaded striker inside the fuse. Releasing the lever (the striker throws it away with a never-to-be-forgotten fiinnnnggggg noise) the striker snaps home and ignites a four-second fuse.
The M-26 can also be used as a booby trap, by fastening it to something, attaching a length of fishline to the pull-ring, then attaching the other end of the line to something else. (They issued you fishline for that purpose.) Or you could simply put something heavy on top of the grenade and remove the pin.
US troops also carried smoke grenades. These were used in several ways. Mostly they were used to mark positions. One was usually tossed out before a helicopter landed, to indicate the wind direction and velocity to the pilot. They were also used as "break contact" devices, a sort of instant smokescreen. The smoke came in several colors, red, violet, yellow, green and black, I think. The color of the smoke was indicated on top of the grenade, as well as by lettering on the side.
M-18 Smoke Grenade
Other types of grenades were less common. Thermite or demolition grenades were filled with a self-igniting welding compound that would melt steel. Its primary use was to destroy abandoned equipment or weapons. CS grenades were filled with tear gas and used on tunnels. WP "Willie Peter" grenades were filled with white phosphorus. This a hellish compound that even burns under water. If even tiny pieces got on you, they would burn right through your body. The only treatment was to QUICKLY pluck them out with the point of a knife. They were used on bunkers, primarily. They exploded with a spectacular display. Finally, there was a limited issue of defoliate grenades. Yes, Agent Orange again. They were used to destroy small VC crops or gardens.
Other US Weapons
The M-14 was the rifle used by all US troops in training, and by support troops in Vietnam. It fired the same 7.62mm NATO cartridges as the M-60 machinegun. It's magazine held 20 rounds, but the ammunition was much heavier and you could only carry 40% the number of rounds for the same weight, compared to the M-16. However the 7.62 NATO bullets had a longer range and greater penetration. Unlike the M-16, it was regarded as completely reliable. though longer and heavier. (Fully loaded, it weighed nearly half again as much as a fully loaded M-16, 11.25 pounds versus 8.1.)
M-21 Sniper Rifle
Because of its inherent accuracy, the Army fitted selected M-14's with a variable magnification (3-9X) Leatherwood telescope sight as the M-21 sniper rifle. Units selected experienced infantry soldiers to attend a 30 day, in-country, training course in the weapon, fieldcraft, and sniper techniques. Graduates were presented with their own M-21's and returned to their units after completing the course.
The Army issued several kinds of shotguns in Vietnam, and GIs often supplanted them with privately purchased commercial shotguns, shipped or brought into the country. All the shotguns ended up more or less the same, 12 gauge, five shot, pump-action, firing buckshot rounds. At close range, they were devastating. At a dozen yards, each round equaled a burst from a 9mm submachinegun.
Other weapons GIs used included WW II vintage American types, especially the M-2 and M-2A1 Carbine. Ammunition for these could still be obtained through the American supply system. After that, any sort of weapon was possible, but ammunition for it would be a problem and a weapon without bullets is a club.
The Soviet-designed AK-47 was also carried, and will be covered under Communist weapons. I should mention that most units required you to carry your assigned weapon, but if you could make a case for something else, you could probably carry that instead. ("Sir, I don't like the M-16, I shot Expert with the 'Fourteen in Basic. I got this 'Fourteen now. Can I carry it? I have nine magazines for it.") Non-standard weapons were the prerogative of leaders, who were armed primarily for self-defense anyway. Of course, carrying a non-standard weapon would mark you out to enemy snipers, so there was that to consider. By the way, in combat units, nobody cared where you got any extra weapon, or other military item you hadn't been issued.