The history of the modern assault rifle began during World War II when German Weapons engineers designed the 'Sturmgewehr'. The Sturmgewehr was the first rifle that could fire a medium size bullet at high rates of fire. Its main advantages were small size and light weight. After World War II, the American Military realized that it needed a new rifle, which would be at least capable of the features of the German Sturmgewehr.
As written by Edward C. Ezell in The Great Rifle Controversy, the development of the M16 rifle began with the research conducted at John Hopkins University in September of 1948. The research was to question infantrymen, who fought in Korea, about their battle experiences. It was found that 95% of their firing was within 300 yards. Also, there were just as many lethal hits from un-aimed shoots as from aimed ones. This information led the military to the conclusion that a .22 caliber rifle capable of selective fire was the best solution.
With this information the military went to Eugene Stoner, a Marine Corps Veteran who started to design rifles after being decommissioned, and asked him if he was interested in designing a weapon based on their research. The requirements for the new weapon were that it had to weight less than 6 pounds loaded, it had to be a .22 caliber, it had to be selective fire capable and it had to be able to penetrate a steel helmet out to 500 meters.
The rifle the military was using up to that date, the old M14, was a heavy, .308 caliber, large, selective fire capable rifle. The benefits of a large caliber like the .308 NATO, which are longer range and greater penetration, were not needed. The rifle has actually some major disadvantages. Due to its large caliber, when fired in full-auto mode the rifle recoils so much, that only the first one or two bullets hit the target. Secondly, the large caliber means that the ammunition itself is quite heavy and large compared to an M16 round, which means that soldiers must carry less ammunition. Its large size and heavy weight make it difficult for soldiers to use during combat situations. Even though, I have to give the M14 some credit. It was very popular among soldiers due to its great reliability. Also, the M14 is still used by the military in limited quantities. To get back to the differences between the M14 and M16, I will explain the advantages of the M16 over the M14.
Because the military demanded a .22 caliber round which could penetrate a steel helmet at 500 meters, Stoner needed a more powerful cartridge than there was currently available. Stoner had Remington Arms company increase the capacity of their .222 Remingt on to fire a 55-grain bullet at 3300 feet per second. This new round meet the criteria, and compared to the .308 NATO caliber round of the M14 it was much lighter, smaller and produced less recoil when fired. Recoil is the force acting on the shooter when firing any kind of powder gun. The larger the caliber is, the more powder is used to propel the bullet out of the barrel, and more powder means more recoil. Compared to the M-14's 10-inch jerk upwards the M-16 jerks only about 2 inches up after firing. Thus, a smaller cartridge, with less recoil keeps the rifle aimed at the target after fired. Because the ammunition is lighter and smaller, soldiers can carry a lot more ammunition. The lower weight of the rifle itself benefits the soldiers simply by less weight, which they have to hold in their hands. Besides that, it made the weapon easier to handle, which was probably the more important factor. When Stoner was designing the M16, he used design features from many different weapons, to create the perfect rifle for the American soldier. Another important aspect included in Stoners' design was the simplicity of the M16 rifle. Stoner eliminated many moving parts, to make the rifle simple to operate and cheaper to manufacture.
When the Army began first tests in March 1958, the rifle was not fully developed yet. There were some problems with the rifle but Stoner fixed them within short periods of time. The only major problem that was not discovered yet was that the Army told its soldiers that the M16 need not to be cleaned. This would have been true if the Army had used the ammunition the M16 was designed for, but instead the army used cheaper ball powder, which clogged up the barrel and lead to malfunctions of the rifle. From Ezell's book I quote:
"When Stoner developed the 5.56mm cartridge, he used a commercial gunpowder called Improved Military Rifle (IMR) powder. Stoner had used this extruded gain propellant because it was cleaner-burning than the ball type specified by the Ordnance Corp. ...transmitted powder residues that tended to dirty up the bolt and bolt carrier assembly, and in turn jam the rifle."
This was quickly taken care of by issuing cleaning kits to the soldiers. Other problems remain to be unseen up to today.
The M16 was first issued to American Soldiers in Vietnam in 1968. Since then, it was adopted by a dozen of military and police forces throughout the world. Operation Desert Storm was one of the more current situations were the M16 has proven itself to be an excellent rifle. The military is discussing to adopt a new rifle as their standard issue rifle. The M4A1, a variant of the M16 rifle has a shorter barrel and an adjustable buttstock. Even though, the M4A1 is not a newly designed weapon, rather a modification of the M16 rifle.
The operational debut of the M16 appeared to go quite well when the rifle was first issued to troops in the battle in the Ia Drang Valley of Viet Nam in early November, 1965. Lieutenant Colonel, later Lieutenant General, Harold G. Moore Junior reported "brave soldiers and the M16 brought" the allied victory. But as the number of M16s "in country" increased, so did the reports of their failure in combat. In May, 1967, one Marine wrote home about it:
"I just got your letter today aboard ship. We've been on an operation ever since the 21st of last month. I can just see the papers back home now - "Enemy casualties heavy, Marine casualties light". Let me give you some statistics and you decide if they were light. We left with close to 1400 men in our battalion and came back with half. We left with 250 men in our company and came back with 107. We left with 72 men in our platoon and came back with 19. I knew I was pressing my luck. They finally got me. It wasn't bad though, I just caught a little shrapnel. I wish I could say the same for all my buddies.
...believe it or not, you know what killed most of us? Our own rifle. Before we left Okinawa, [we] were all issued this new rifle, the M16. Practically everyone of our dead was found with his rifle torn down next to him where he had been trying to fix it. There was a newspaperwoman with us photographing all this and the Pentagon found out about it and won't let her publish the pictures. They say that they don't want to get the American people upset. Isn't that a laugh?"
This got posted on another forum I go to in a thread involving the "Replace the M16!" article that already got torn up here as being stupid.
I know most of it's crap, like Stoner designing the AR-15 (and no mention of the AR-10), but figured you guys could pull it apart better than I can.