The M16 is Here to Stay

The United States Marines are finally getting rid of their M-16A4 rifles. The replacement will be smaller, lighter and will require almost no retraining. It will allow the Marines more mobility and make firing from vehicles much easier. It’s the M4, The M-16s shorter brother.


The M-16’s design traces it’s lineage back over nearly 60 years. First conceived of as the Armalite AR-10 in the mid-1950s. The battle rifle was chambered in 7.62 NATO and utilized jet age aluminium and polymer construction. In 1957 the rifle was slightly redesigned and re-chambered in 5.56 x 45. Armalite redesignated it the AR-15 and in 1963 the AR-15 was adopted by the U.S military as the M-16.

Over the years the M-16 underwent several major upgrades and modifications. The A1 model introduced a chrome-lined  bore to increase reliability, a forward assist to help with jams and a new flashhider. Eventually,a shell case deflector was also added to prevent spent casings from ejecting into the faces of left-handed soldiers .

Throughout the last 30 years rail systems, more accurate barrels and heavier cartridges have been introduced to increase lethality. The latest versions (the M4 series) have cut the 20 inch barrel down to 14.5 inches and replaced the fixed stock with a collapsible one to increase portability. The fixed carrying handle has also been replaced with a removable one with rails underneath for mounting optics.

Vietnam M16
Two soldiers engage hostiles with M16A1 rifles in Vietnam

While some may view the M4 as a different rifle, this is a bit of a stretch. The only real differences between the two rifles are the stock, the length of the barrel, and necessary readjustment of the gas system. Everything else remains unchanged. The two rifles share an 80 percent parts commonality . In essence, it’s the same rifle the U.S has had for the last 53 years; just a bit shorter.

53 years of stagnation

Before the basic M-16 rifle was adopted in the early 1960s the United States introduced a new infantry rifle every few decades. In the 50 years after the Springfield was introduced in 1903 the U.S went through four rifles and five different cartridges. In the 53 years since then, the U.S has only officially adopted one new standard rifle; the M4. The military has kept the same cartridge and rifle; making only small changes to it’s cartridge weight, exterior, and barrel length.

Operation Iraqi Freedom
A soldier from the 82d Airborne Division on February 12, 2004 during Operation Iraqi Freedom. An M4 carbine hangs from it’s straps as the soldier uses the radio. Photo by Staff Sgt. Charles B. Johnson

This is not for lack of trying. The U.S has tried to replace the M-16 on multiple occasions. In the late 1980s and early 1990s the Advanced Combat Rifle program was an attempt to replace the M-16 with a rifle with better hit probability and more advanced technologies. This led to the Objective individual Combat Weapon Program in the 1990s. The OICW resulted to the XM8 rifle, which was cancelled in 2005 without being adopted. Recently, the Individual Carbine Competition also attempted to replace the M-16 with a better rifle.

The result? It was determined that the M4 could be upgraded to meet all of the needs of the ICP. The review went as far a to call the program itself a waste of money. After more than 50 years, the M-16 is still alive and still being developed.

A global trend 

America is not the only country that hasn’t changed it’s rifle. Russia still uses the AK-74s it developed in the 1970s. These are basically AK-47s (or AKMs if you want to get technical) re-chambered in the smaller 5.45 cartridge. The Russian design then, is even older than the M-16.

While the Russian’s have experimented with the AN-94 rifle, it was not widely bought or issued. Their AK-100 series is more of the same.They are Kalashnikov rifles with folding butt-stocks and polymer furniture. Some have experimented with balanced gas systems. But still, they are basically Kalashnikovs.

The story is the same in every other country. Every military on earth fields select-fire rifles chambered in either 5.56 or 7.62 NATO or the Russian 7.62 x 39 or 5.45 x 39. While new designs continue to come out, they all use the same gas systems and locking mechanisms. It all ends up the same; an eight pound select fire rifle with plastic furniture and an expensive optic stuck to the top rail.

So Why?


In the late 80s and early 90s there where many promising technologies for increasing the effectiveness of military rifles. flechettes, caseless ammunition and hyperburst features were all tested in an attempt to build a better gun.

Caseless Ammo

None of these panned out. Caseless ammunition was one example. Although it made ammunition lighter It proved sensitive to environmental factors like moisture and had basic mechanical problems.

One of those problems was extraction. If a round failed to fire there would be no way to get it out of the chamber. Most modern extractors grab the case rim to remove it from the chamber. But being caseless there is nothing for the mechanism to grab. Without a rim there would be no way to quickly clear a malfunction. On the M-16 all one has to do is pull the charging handle back and it will (hopefully) eject the round and chamber a new one. On a caseless rifle it would likely require the operator to disassemble the rifle.

It was also extremely hard to keep the gun cool enough to fire. The brass in a standard rifle acts as a heat-sink that pulls thermal energy out of the chamber when ejected. Under sustained fire the chamber of a caseless rifle could get hot enough to ignite a rounds propellant and the rifle could fire with input from the user (a”cook off”).


Flechettes had problems as well. Although theoretically lighter, faster  and more suited to hyperburst, they were not as accurate as bullets and their low mass meant that they were not very good at penetrating barriers or actually inflicting fatal wounds on enemy combatants.

A round of caseless ammunition, disassembled


There are costs involved in switching rifles. Soldiers need to be retrained and the industrial base has to tool up to produce them. Economies of scale means the new rifles are going to be much more expensive initially no matter how simple or complex they are.

Hyperburst technology have usually required a special mechanism to achieve the extreme fire rate for the burst mode. The mechanism makes the insides less of a rifle and more like a Swiss watch. This mechanical complexity adds enormously to the cost of producing the rifles.

Caseless ammo adds even more cost. lacking a brass case to expand and seal the breach, the tolerances around the chamber have to be extremely tight unless the gas from the burning powder will leak. Although the ammo can be made smaller and lighter, accommodating it also means that the rifles will cost even more to produce.

This is what the G11 looks like on the inside. The G11 used caseless ammo and had a hyperburst feature


After the Cold War ended, advanced concepts like these were shelved. Budgets were cut across NATO, and Russia simply ceased to compete with the West militarily. Given these considerations, adopting a new, more expensive and complicated weapon was simply not in the cards.

They All Failed

But probably the most important issue with these programs was that none of them managed to actually achieve a substantial improvement over the M-16/M-4 in terms of combat characteristics. Even the flechette concepts failed to beat the M-16A2 in a hit probability trial. The trade-off simply wasn’t worth it. So, the the military stuck with the M-16.


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