AR-15/M16: The Rifle That Was Never Supposed to Be

The SR25, perhaps the most accurate autoloader on the face of the earth. Gene Stoner revives his original AR10 design, with some added features of the M16A2, to build this semi-automatic 7.62×51 mm sniper rifle.

The SR25, perhaps the most accurate autoloader on the face of the earth. Gene Stoner revives his original AR10 design, with some added features of the M16A2, to build this semi-automatic 7.62×51 mm sniper rifle.

This article is an excerpt from the Gun Digest Book of Classic Combat Rifles.

Military surgeons all over the world have asked the United Nations to ban small caliber high-velocity rounds in combat — including the 5.56×45mm and the 5.45×39mm cartridges — which they believe cause unnecessary pain and suffering.

Switzerland re-designed the M855/SS109 round with a thicker jacket to stop fragmentation upon impact.

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This article is an excerpt from the Gun Digest Book of Classic Combat Rifles. Click the cover to order this book and read more gun histories.

This new cartridge, however, was significantly more accurate at longer ranges than the M193 Ball cartridge, boosting the maximum effective range to 800 meters. To accommodate this new cartridge, a new barrel twist — from 1:12 inches to 1:7 inches — was required to stabilize the heavier 62-grain bullet.

There was a catch: the SS109 ammunition could not be fired accurately in an M16/M16A1 rifle due to its slower rifling twist. The bullet would not stabilize and would “keyhole” in flight. This new cartridge was about to be adopted as the M855 Ball cartridge of the U.S. military and the new PIP project would redesign the M16A1 rifle around this cartridge.

The United States Marine Corps began negotiations with Colt in January of 1980, asking for three modified rifles that would make use of the new FN SS109/XM855 cartridge and would incorporate four Marine-designated changes:

1. The sights must be adjustable to 800 meters.
2. The bullet must be accurate to 800 meters and possess the capability to penetrate all known steel helmets and body armor at 800 meters.
3. The strength of the plastic stock, pistol grip and handguards ­ — as well as the strength of the exposed portion of the barrel — must be improved.
4. The rifle must have the full-auto capability replaced with a 3-shot burst mode.

The Joint Services Small  Arms Program (JSSAP) PIP

The first rifles arrived from Colt in November of 1981. The USMC Firepower Division at Quantico, Virginia, would lead the PIP project. On November 11th, 20 Marines and 10 soldiers from the 197th Infantry Brigade at Fort Benning, Georgia, would take 30 M16A1 rifles and 30 M16A1E1 (PIP rifles) and test them for a month.

The test report was issued on December 11th and the conclusions were as follows:
• The sights were easily adjusted in the field by hand rather than with a bullet tip.
• Increased the effectiveness at long range, more so than the M16A1.
• More durable plastic furniture on the M16A1E1, for hand-to-hand combat.
• Sights were better for low-light conditions thanks to a larger-diameter (5mm) close-range aperture in the rear sight.
• Increased ammunition conservation and more effective fire with the 3-round burst than with full-auto fire.
• Utilized the XM855 NATO (SS109) ammunition, which improves the accuracy and penetration at all ranges. The product-improvement (PIP) “M16A1E1” was classified as the M16A2 in September of 1982 and was adopted by the United States Marine Corps in November of 1983. The Marines ordered 76,000 M16A2 rifles from Colt. The Army did not adopt the M16A2 until 1986.

4 thoughts on “AR-15/M16: The Rifle That Was Never Supposed to Be

  1. master gunny

    As the armorer for the 6th Engineer Bn I one had to use a hammer and screwdriver to force the bolt into full battery (with a round in the chamber!) in order to clear a malfunction. I was shocked because the weapons was not anywhere dirty enough to explain the severe malfunction. That same day I have another stoppage, same problem, but again the fowling was not that severe. I could go on and on with why I feel the weapon is a poor choice for an infantrymen but suffice to say that I will stick with my M1A and HK-91.

  2. master gunny

    With respects it’s obvious to me that you guys are too young to remember the controversy surrounding the introduction of the M-16. Not mentioned in yourt article were the constant complaints about the weapons, their unreliability, the congressional hearings on the malfunctions that that were literally getting our tropps killed in Vietnam. Numerous accounts of troops found dead in their fighting holes with their weapons diassembled were presented as evidence that the weapon was despised by the troops. Mothers would get urgent letters from their sons asking for cleaning gear and solvents because the weapons fouled so easily and severely. The forward assist, and chrome chamber were just a couple of the modifications necessary to solve some of the problems.

    More offensive to me was the remark that the M14 was prone to jams and problems and speaking from experience I can tell you that is exactly the opposite of the truth. The M14 was rock solid reliable, accurate, and robust. The M1-16 fragile, unreliable, ualofre

  3. tinock28

    I liked the article on the AR-15/M16 rifle very much, I remember an article back in 1956-57 in one of Gun Mag’s about the AR-10, I thougt at the time it was a good rifle.

    1. master gunny

      Read Colonel Moore’s book, “We were soldiers one and Young” to get a better understanding of how critical reliability is to a grunt. One passage, regarding Lt. Herricks surounded platoon, say it all. Troops fighting for their lives against overwhelming odds were forced to discard their weapons and pick up those of their wounded comrades in order to stay in the fight. Many times those weapons were also not functioning and so the troops had to rummage through the perimeter to find a working weapon. Trust me, that sucks