Comparison of the AK-47 and M16

The two most common assault rifles in the world are the Russian AK-47 and the American M16. These Cold War rivals have faced each other in conflicts both large and small since the early 1960s. They are used by military, police, security forces, revolutionaries, terrorists, criminals and civilians alike and will most likely continue to be used for decades to come. As a result, they have been the subject of countless comparisons and endless debate. This article explores the history, philosophies and the issues behind these debates in a chronological, measure vs. countermeasure format.

History


The Germans were the first to pioneer the assault rifle concept, during World War II, based upon research that showed that most firefights happen within 400 meters and that contemporary rifles were over-powered for most small arms combat. The Germans sought to develop a select-fire intermediate powered rifle combining the firepower of a submachine gun with the accuracy and range of a rifle. This was done by shortening the standard 7.92x57mm cartridge to 7.92x33mm and giving it a lighter 125 grain bullet, that limited range but allowed for more controllable automatic fire The result was the Sturmgewehr 44, which the Germans produced in large numbers; approximately half-a-million were made. Unlike previous rifle designs it introduced an over-the-barrel gas system, straight stock and pistol grip to reduce recoil and improve handling characteristics. "The principle of this weapon...was probably the most important advance in small arms since the invention of smokeless powder."

Like the Germans, the Soviets were influenced by experience showing most combat happens within 400 meters and that their soldiers were consistently outgunned by heavily armed German troops, especially those armed with the Sturmgewehr 44 assault rifles. On July 15, 1943, a Sturmgewehr was demonstrated before the People's Commissariat of Arms of the USSR. The Soviets were so impressed with the Sturmgewehr, that they immediately set about developing an intermediate caliber automatic rifle of their own, to replace the badly outdated Mosin-Nagant bolt-action rifles and PPSh-41 submachine guns that armed most of the Soviet Army.

The Soviets soon developed the 7.62x39mm M43 cartridge, the semi-automatic SKS carbine and the RPD light machine gun. Shortly after World War II, the Soviets developed the AK-47 assault rifle, which would quickly replace the SKS in Soviet service. The AK-47 was finalized, adopted and entered widespread service in the Soviet army in the early 1950s. Its firepower, ease of use, low production costs, and reliability was perfectly suited for the Red Army's new mobile warfare doctrines. In the 1960s, the Soviets introduced the RPK light machine gun, itself an AK-47 type weapon with a stronger receiver, a longer heavy barrel, and a bipod, that would eventually replace the RPD light machine gun.

The AK-47 was widely supplied or sold to nations allied with the USSR and the blueprints were shared with several friendly nations (the People's Republic of China standing out among these with the Type 56). As a result, more AK-type weapons have been produced than all other assault rifles combined. Astonishingly, "Of the estimated 500 million ﬁrearms worldwide, approximately 100 million belong to the Kalashnikov family, three-quarters of which are AK-47s."

The U.S. Army was influenced by combat experience with semi-automatic weapons such as the M1 Garand and M1 carbine, which enjoyed a significant advantage over enemies armed primarily with bolt-action rifles. Although U.S. Army studies of World War II combat accounts had very similar results to that of the Germans and Soviets, the U.S. Army failed to recognize the importance of the assault rifle concept, and instead maintained its traditional views and preference for high-powered semi-automatic rifles.

After World War II, the United States military started looking for a single automatic rifle to replace the M1 Garand, M1/M2 Carbines, M1918 Browning Automatic Rifle, M3 "Grease Gun" and Thompson submachine gun. Early experiments with select-fire versions of the M1 Garand proved disappointing. Also, combat experience suggested that the .30 Carbine round was underpowered. American weapons designers reached the same conclusion as the Germans and Soviets: an intermediate round was necessary, and recommended a small-caliber, high-velocity cartridge.

However, senior American commanders having faced fanatical enemies and experienced major logistical problems during WWII and the Korean War,    insisted that a single powerful .30 caliber cartridge be developed, that could not only be used by the new automatic rifle, but by the new general purpose machine gun (GPMG) in concurrent development. This culminated in the development of the 7.62x51 NATO cartridge and the M14 rifle which was basically an improved select-fire M1 Garand with a 20 round magazine. The U.S. also adopted the M60 GPMG. Its NATO partners adopted the FN FAL and HK G3 rifles, as well as the FN MAG and Rheinmetall MG3 GPMGs.

The first confrontations between the AK-47 and the M14 came in the early part of the Vietnam War. Battlefield reports indicated that the M14 was uncontrollable in full-auto and that soldiers could not carry enough ammo to maintain fire superiority over the AK-47. A replacement was needed: A medium between the traditional preference for high-powered rifles such as the M14, and the lightweight firepower of the M2 Carbine. As a result, the Army was forced to reconsider a 1957 request by General Willard G. Wyman, commander of the U.S. Continental Army Command (CONARC) to develop a .223 caliber (5.56 mm) select-fire rifle weighing 6 lbs (2.7 kg) when loaded with a 20 round magazine. The 5.56mm round had to penetrate a standard U.S. helmet at 500 yards (460 meters) and retain a velocity in excess of the speed of sound, while matching or exceeding the wounding ability of the .30 Carbine cartridge.

This request ultimately resulted in the development of a scaled-down version of the Armalite AR-10, called AR-15 rifle. However, despite overwhelming evidence that the AR-15 could bring more firepower to bear than the M14, the Army opposed the adoption of the new rifle. In January 1963, Secretary of Defense Robert McNamara concluded that the AR-15 was the superior weapon system and ordered a halt to M14 production. At the time, the AR-15 was the only rifle available that could fulfill the requirement of a universal infantry weapon for issue to all services. After modifications (Most notably: the charging handle was re-located from under the carrying handle like AR-10 to the rear of the receiver), the new redesigned rifle was subsequently adopted as the M16 Rifle.

Despite its early failures the M16 proved to be a revolutionary design and stands as the longest continuously serving rifle in American military history. It has been adopted by many U.S. allies and the 5.56x45mm cartridge has become not only the NATO standard, but "the standard assault-rifle cartridge in much of the world." It also led to the development of small-caliber high-velocity service rifles by every major army in the world, including the USSR and People's Republic of China. Today, many small arms experts consider the M16 the standard by which all other assault rifles are judged.

M16
The M16 is a select-fire, 5.56x45mm, air-cooled, direct impingement gas-operated, magazine-fed rifle, with a rotating bolt and straight-line recoil design. It was designed above all else to be a lightweight assault rifle, and to fire a new lightweight, high velocity small caliber cartridge to allow the soldier to carry more ammunition. It was designed to be manufactured with the extensive use of aluminium and synthetic materials by state of the art Computer Numerical Control (CNC) automated machinery.

At peak production, Colt's manufacturing capacity was approximately 333,000 units per year The M16 continues to benefit from every advance in the CNC field, which allows more and more small manufacturers to mass-produce M16s and semi-automatic AR-15 type rifles. The M16's aluminum lower receiver may be forged or cast, or made from a variety of other metallic alloys, composites and polymers. If necessary, it can be machined from a billet of steel and fitted with wooden furniture. This makes the M16 ideal for market economy production, spread among many small manufacturers around the country, using a variety of materials and manufacturing methods; this ensures it would be nearly impossible to disrupt U.S. M16 production in the case of a major conflict. The M16 is a Modular Weapon System. It is easy to assemble, modify and repair using a few simple hand tools, and a flat surface to work on.

As of 2012, the United States military buys M4 Carbines for $673 (USD) per unit. Approximately 8 million M16 type rifles have been made worldwide.

AK-47
The AK-47 is a select-fire, 7.62x39mm, air-cooled, long-stroke-piston gas-operated, magazine-fed rifle, with a rotating bolt. It was designed to be a simple, reliable automatic rifle that could be manufactured quickly and cheaply, using mass production methods that were state of the art in the Soviet Union during the late 1940s. The AK-47's barrel and bolt were milled out of a steel billet and hard chromed. Its receiver was originally designed to be stamped from sheet metal with a milled trunnion insert. However, there were many difficulties during the initial phase of production causing high rejection rates. Instead of halting production, a heavy machined receiver was substituted for the sheet metal receiver. This was a more costly and time consuming process, but advanced the programs development and accelerated production. In 1959, the sheet metal stamping process was perfected, simplifying manufacture and reducing the weight of the rifle from 3.87 kg to 2.93 kg without magazine. The stock was simply made out of wood, which was a non-strategic material, and perfectly fits the Soviet manufacturing philosophy, where large manufacturing plants produce basic weapons in very large quantities.

At peak production, Kalashnikov Concern (formerly Izhmash) can produce around 95 units per hour (about 832,000 units per year). Over time, AK-47 descendants have been simplified through the use of spot welding and by further reducing the number of machined parts. Because of its stamped-steel design it is not possible to manufacture the AK-47 series efficiently in small plants, due to the large amount of metal stamping equipment needed for mass production. However, the milled-steel AK-47 has spawned a cottage industry of sorts and has been copied and manufactured (one gun at a time) in small shops around the world.

As of 2011, Kalashnikov Concern (formerly Izhmash) sells the AK-103 at a government price of $150 to $160 (USD) per unit. There are places around the world where an AK-47 type rifle can be purchased on the Black Market "...for as little as $6, or traded for a chicken or a sack of grain." Approximately 100 million AK-47 type rifles have been made worldwide.

Size and weight
Note *: Most of the AK type rifles in use today are of the lighter stamped-steel AKM variety. Note **: The M16A2 weighs more and is slightly longer than the original, with the addition of heavier (and more accurate) barrels, improved sights and more rugged furniture. Note ***: Earlier versions of the AK used wood furniture, the type and density of which causes the AKs weight to vary. Whereas, the M16 and current models of the AK use synthetic materials, which have consistent weights.

Sights
The M16 has a 500mm (19.75 inches) sight radius. The M16 uses an L-type flip, aperture rear sight and it is adjustable with two setting, 0 to 300 meters and 300 to 400 meters. The front sight is a post adjustable for elevation in the field. The rear sight can be adjusted in the field for windage. The sights can be adjusted with a bullet tip and soldiers are trained to zero their own rifles. The sight picture is the same as the M14, M1 Garand, M1 Carbine and the M1917 Enfield. The M16 also has a "Low Light Level Sight System", which includes a front sight post with a small glass vial of (glow-in-the-dark) radioactive Tritium H3 and a larger aperture rear sight. The M16 can mount a scope on the carrying handle. With the advent of the M16A2, a new fully adjustable rear sight was added, allowing the rear sight to be dialed in for specific range settings between 300 and 800 meters and to allow windage adjustments without the need of a tool or cartridge. Current issue M16A4s and M4s have detachable carrying handles and use Picatinny rails which allow for the use of various scopes and sighting devices. The current United States Army and Air Force issue M4 Carbine comes with the M68 Close Combat Optic and Back-up Iron Sight. The United States Marine Corps uses the ACOG Rifle Combat Optic and the United States Navy uses EOTech Holographic Weapon Sight.

The AK-47 has a 378mm (14.88 inches) sight radius. The AK-47 uses a notched rear tangent iron sight, it is adjustable and is calibrated in hundreds from 100 to 800 meters (100 to 1000 meters for AKM models). The front sight is a post adjustable for elevation in the field. Windage adjustment is done by the armory before issue. The "fixed" battle setting can be used for all ranges up to 300 meters. This "point-blank range" setting marked "П", allows the shooter to fire at close range targets without adjusting the sights. Longer range settings are intended for area suppression. These settings mirror the Mosin-Nagant and SKS rifles which the AK-47 replaced. Some AK type rifles have a front sight with a flip-up luminous dot that is calibrated at 50 meters, for improved night fighting. All current AK-47s (100 series), have a side rail for mounting a variety of scopes and sighting devices, such as the PSO-1 Optical Sniper Sight. However, their side folding stocks cannot be folded with the optics mounted.

Ammunition
A brief comparison between cartridges reveals that the M16's lighter, higher-velocity 5.56×45mm cartridge has much better range and accuracy, and that the AK-47's heavier 7.62×39mm cartridge has much better penetration. Note *:The effective range of a firearm is the maximum distance at which a weapon may be expected to be accurate and achieve the desired effect. Note **: The lethal range is the maximum range of a small-arms projectile, while still maintaining the minimum energy required to put a man out of action, which is generally believed to be 15 kilogram-meters (108 ft.-Ibs.). This is the equivalent of the muzzle energy of a .22LR handgun. Note ***: The maximum range of a small-arms projectile is attained at about 30° elevation. This maximum range is of only safety interest, not for combat firing.

The M16 has always enjoyed a reputation for excellent accuracy. Its light recoil, high-velocity and flat trajectory allow shooters to take head shots out to 300 meters. "In Fallujah, Marines with ACOG-equipped M16A4s created a stir by taking so many head shots that until the wounds were closely examined, some observers thought the insurgents had been executed." Whereas, the AK-47's accuracy has always been considered to be "good enough" to hit an adult male torso out to about 300 meters.

The newer M16 models are more accurate than their predecessors and are capable of shooting 1–3 inch groups at 100 yards. Curiously, the newer stamped steel receiver AKM models are actually less accurate than their predecessors. "There are advantages and disadvantages in both forged/milled receivers and stamped receivers. Milled/Forged Receivers are much more rigid, flexing less as the rifle is fired thus not hindering accuracy as much as stamped receivers. Stamped receivers on the other hand are a bit more rugged since it has some give in it and have less chances of having metal fatigue under heavy usage." As a result, the milled AK-47's are capable of shooting 3–5 inch groups at 100 yards, whereas the stamped AKM's are capable of shooting 4–6 inch groups at 100 yards.

The AK-47's heavier 7.62x39mm round has superior penetration when compared to the M16's lighter 5.56x45mm round and is better in circumstances where a soldier has to shoot through heavy foliage, walls or a common vehicle's metal body and into an opponent attempting to use these things as cover. The 7.62x39mm M43 projectile does not generally fragment and has an unusual tendency to remain intact even after making contact with bone. The 7.62x39mm round produces significant wounding in cases where the bullet tumbles in tissue, but produces relatively minor wounds in cases where the bullet exits before beginning to yaw. In the absence of yaw, the M43 round can pencil through tissue with relatively little injury.

The original ammunition for the M16 was the 5.56x45mm M193 round. When fired from a 20″ barrel at ranges of up to 100 meters, the thin-jacketed lead-cored round traveled fast enough (above 2900 ft/s) that the force of striking a human body would cause the round to yaw (or tumble) and fragment into about a dozen pieces of various sizes thus created wounds that were out of proportion to its caliber. These wounds were much larger than those produced by AK-47 and they were so devastating that many considered the M16 to be an inhumane weapon. As the 5.56mm round's velocity decreases, so does the number of fragments that it produces. The 5.56mm round does not normally fragment at distances beyond 200 meters or at velocities below 2500 ft/s, and its lethality become largely dependent on shot placement.

In March 1970, the U.S. recommended that all NATO forces adopt the 5.56x45mm cartridge. This shift represented a change in the philosophy of the military's long-held position about caliber size. By the middle of the 1970s, other armies were looking at M16-style weapons. A NATO standardization effort soon started and tests of various rounds were carried out starting in 1977. The U.S. offered the 5.56x45mm M193 round, but there were concerns about its penetration in the face of the wider introduction of body armor. In the end the Belgian 5.56x45mm SS109 round was chosen (STANAG 4172) in October 1980. The SS109 round was based on the U.S. cartridge but included a new stronger, heavier, 62 grain bullet design, with better long range performance and improve penetration (specifically, to consistently penetrate the side of a steel helmet at 600 meters). Due to its design and lower muzzle velocity (about 3110 ft/s) the Belgian SS109 round is considered more humane because it is less likely to fragment than the U.S. M193 round. The NATO 5.56x45mm standard ammunition produced for U.S. forces is designated M855.

Most, if not all, of the 7.62x39mm ammunition found today is of the upgraded M67 variety. This variety deleted the steel insert, shifting the center of gravity rearward, and allowing the projectile to destabilize (or yaw) at about 3.3 inches, nearly 6.7 inches earlier in tissue than the M43 round. There is now relative parity between the wounding capacity of the M67 and the current M855 5.56x45mm round. However, there have been repeated and consistent reports of the M855's inability to wound effectively (i.e. fragment) when fired from the short barreled M4 carbine (even at close ranges). The M4's 14.5" barrel length reduces muzzle velocity to about 2900 ft/s. This reduced wounding ability is one reason that, despite the Army's transition to short-barrel M4's, the Marine Corps has decided to continue using the M16A4 with its 20″ barrel as the 5.56x45mm M855 is largely dependent upon high velocity in order to wound effectively.

The U.S. Army contended in 2003 that the lack of lethality of the 5.56x45mm was more a matter of perception than fact. With good shot placement to the head and chest, the target was usually defeated without issue. The majority of failures were the result of hitting the target in non-vital areas such as extremities. However, a minority of failures occurred in spite of multiple hits to the chest. A study in 2006 found that 20% of soldiers using the M4 Carbine wanted more lethality or stopping power. In June 2010, the United States Army announced it began shipping its new 5.56mm, lead-free, M855A1 Enhanced Performance Round to active combat zones. This upgrade is designed to maximize performance of the 5.56x45mm round, to extend range, improve accuracy, increase penetration and to consistently fragment in soft-tissue when fired from the not only standard length M16s, but also the short-barreled M4 carbines. The U.S. Army has been so impressed with the new M855A1 EPR round that they’re now developing a 7.62 NATO variant.

In the mid-1960s, the USSR saw the advantages of a high-velocity small-caliber cartridge and began to develop the AK-74 and the 5.45x39mm cartridge, which offers improved range and accuracy over the AKM and the 7.62x39mm cartridge. However, the AK-74s range and accuracy is still "inferior to most Western weapons," including current issue M16 type rifles. The 5.45mm cartridge is also lighter than the 7.62mm cartridge allowing soldiers to carry more ammo. In addition, it offers better penetration than the U.S. round. Although, unlike its counterpart the 5.45mm round “does not deform or fragment when striking soft tissues.” Nevertheless, during the Afghan war the Mujahedeen called the 5.45x39mm round the "Poison Bullet" due to the severe wounds it produced to extremities and the resulting need to amputate.

During the 1990s, the Russians developed the AK-101 in 5.56x45mm NATO for the world export market. In addition, Bulgaria, Czechoslovakia, Hungary, Poland and Yugoslavia (i.e. Serbia) have also rechambered their locally produced AK variants to 5.56mm NATO. And, Finland, Israel, South Africa and Sweden have made AK type rifles in 5.56x45mm since the 1970s.

Firepower
Rates Of Fire

Both the AK-47 and the M16 are select-fire weapons capable of firing in semi-automatic and full-auto, or semi-auto and 3-round-burst for the later model M16s. However, the semi-auto and 3-round-burst capability of the M16A2 and later models have less combat capability than their predecessors or AK-47 type rifles. This is due to the elimination of full-auto mode of fire In addition, the burst mechanism does not recycle; if one or two rounds are fired because the trigger is not held long enough, the next pull of the trigger will not result in a three-round burst, but will result in one or two shots being fired. Note *: The AK-47 does not have a three round burst capability. The M16A2 and later models have replaced the full-auto mode of fire with a three round burst capability. Note **: Both the AK-47 and the M16 will overheat fairly quickly under normal combat conditions and have a sustained rate of fire as low as 12 to 15 rounds per minute (about the same as a bolt-action rifle).

Available firepower

The single most limiting factor in terms of firepower is the amount of ammo that a soldier can carry. A soldier armed with an M16 can carry far more ammunition than a soldier armed with an AK-47. Assuming a maximum 10 kilogram ammo-load... Note *: 10 kg is the maximum amount of ammo that the average soldier can comfortably carry... it also allows for best comparison of the three most common AK-47 magazines to the standard USGI M16 magazine.

Additional firepower

Note: All of these grenades, launchers and shotguns add additional bulk and weight to the soldiers war-load and as a result, they reduce the amount rifle ammunition that soldiers can carry. For example, a modern French AC58 "bullet trap" rifle grenade is 380mm long and weighs .5 kg, the equivalent of a loaded M16 magazine. An M203 grenade launcher adds 1.4 kg to an M16's weight and 40x46mm High Explosive (HE) grenades weigh .24 kg, about half the weight of a loaded M16 magazine.

Recoil
With the proper mind-set, training and practice, soldiers armed with both the AK-47 and M16 are quite deadly. However, the M16's direct impingement gas operation system, straight-line recoil design and smaller caliber gives it less recoil than the AK-47 and makes it easier to control in full-auto.

The M16's direct impingement gas operation system has the advantage of having the absolute minimum of recoiling action parts, resulting in the minimum possible weapon disturbance due to balance shifting during the action cycle as well as reducing overall weapon weight. The M16's straight-line recoil design, where the recoil spring is located in the stock directly behind the action, and serves the dual function of operating spring and recoil buffer. The stock being in line with the bore also reduces muzzle rise, especially during automatic fire. Because recoil does not significantly shift the point of aim, faster follow-up shots are possible and user fatigue is reduced. Also, current model M16 flash-suppressors also act as compensators to reduce recoil further.

With the AK-47's long-stroke piston gas system, the piston is mechanically fixed to the bolt group and moves through the entire operating cycle. The primary disadvantage to this system is the disruption of the point of aim due to the center of mass changing during the action cycle and energetic and abrupt stops at the beginning and end of bolt carrier travel. However, the AK-47's heavier weight and slower rate-of-fire do a good job at mitigating any disadvantage. In addition, newer AK-47 type rifles use a muzzle brake or compensator to reduce recoil. And, some AK type rifles also have vertical foregrips to improve handling characteristics and to counter the effects of recoil.

Notes: Free Recoil is mathematical equation calculated by using the rifle weight, bullet weight, muzzle velocity and charge weight. It is that which would be measured if the rifle were fired suspended from strings, free to recoil. As mentioned above, a rifles perceived recoil is also dependent on many other factors which are not readily quantified.

Accessories
Neither the AK-47 nor the M16 were designed to mount accessories, except of course for their respective bayonets and a simple clamp type bipod for the M16. However, with the advent of the Picatinny rail and by sheer happenstance, the M16 has proven itself to be a remarkably adaptable weapon system, capable of mounting a wide range of accessories, including grenade launchers, fore-grips, removable carry handle/rear sight assemblies, bipods, laser systems, electronic sights, night vision, tactical lights, etc. The AK-47 can also use Picatinny rail mounted accessories, although its design and smaller fore-stock make it less adaptable.

In addition, the M16 is "the Swiss Army knife of rifles" a modular weapon system whose components can be arranged in a variety of different configuration. For example,…An M16A2 with its standard iron sights and a standard fore-stock can be easily converted, in a matter of seconds and without the use of tools to an M16A4 with Picatinny rails, optical sights and an variety of accessories. Simply by pushing in two pins, removing the A2 upper receiver/barrel and replacing it with an A4 upper receiver/barrel. Or, an M16A4 Rifle can be converted to an M4 Carbine in a few minutes by replacing the upper receiver/barrel and using simple hand-tools to replace the fixed buttstock with a telescoping buttstock. As such, the M16 can be easily converted into different calibers and different types of weapons. The AK-47 has no such capability.

Bayonets

The M16 is 44.25 inches (1124mm) long with an M7 bayonet attached. The M16s M7 bayonet is based on earlier designs such as the M4, M5, & M6 bayonets. All of which are direct descendants of the M3 Fighting Knife and have spear-point blade with a half sharpened secondary edge. The newer M9 bayonet has a clip-point blade with sawteeth along the spine, and can be used as a multi-purpose knife and wire-cutter when combined with its scabbard. The current USMC OKC-3S bayonet bears a resemblance to the Marines' iconic Ka-Bar fighting knife with serrations near the handle.

The AK is 40.15 inches (1020mm) long with an AKM type bayonet attached. The AK-47 has an adequate but unremarkable bayonet. However, the AKM Type I bayonet (introduced in 1959) was a revolutionary design. It has a Bowie style (clip-point) blade with sawteeth along the spine, and can be used as a multi-purpose knife and wire-cutter when combined with its steel scabbard. This designed was copied by other Nations and formed the basis of the US M9 bayonet. The AK-74 bayonet (introduced in 1983) represents a further refinement of the AKM bayonet. "It introduced a radical blade cross-section, that has a flat milled on one side near the edge and a corresponding flat milled on the opposite side near the false edge. The blade has a new spear point and an improved one-piece molded plastic grip making it a more effective fighting knife. It also has saw-teeth on the false edge and the usual hole for use as a wire-cutter. Some Chinese AK type rifles such as the Type 56 include an integral folding spike bayonet, similar to the SKS rifle.

Reliability
The AK-47 has always enjoyed a reputation for rugged reliability and has a malfunction rate of one per 1000 rounds fired. It uses a long-stroke gas system, where the gas is sent from the barrel to push a piston attached to the bolt carrier, thus operating the action. The gas tube is fairly large and is visible above the barrel with ports or vents to allow the excess "dirty" gas to escape without affecting the action. The AK-47 is often built with generous clearances, allowing it to function easily in a dirty environment with little or no maintenance. This makes it reliable but less accurate.

The M16 has always had a reputation for poor reliability and has a malfunction rate of two per 1000 rounds fired. It uses a direct impingement gas system, similar to normal gas operation in principle, but unique in operation. The gas is sent from the barrel, through the gas tube, directly to the inside of the receiver where it passes thru the bolt carrier key, and then into the bolt carrier, expanding in a chamber composed of the inside of the bolt carrier, and the rear of the bolt, where it pushes the bolt forward, and the bolt carrier rearward to start the cycle. When the bolt unlocks, some gas is vented out the ejection part, but some stays within the receiver. This design is much lighter and more compact than a gas-piston design. However, this design requires that combustion byproducts from the discharged cartridge be blown into the receiver as well. This accumulating carbon and vaporized metal build-up within the receiver and bolt-carrier negatively affects reliability and necessitates more intensive maintenance on the part of the individual soldier. The DI operation increases the amount of heat that is deposited in the receiver while firing the M16 and causes essential lubricant to be "burned off". This requires frequent and generous applications of appropriate lubricant. Lack of proper lubrication is the most common source of weapon stoppages or jams.

The original M16 fared poorly in the jungles of Vietnam and was infamous for reliability problems in the harsh environment. As a result, it became the target of a Congressional investigation. The investigation found that:

"# The M16 was billed as self-cleaning (when no weapon is or ever has been).
 * 1) The M16 was issued to troops without cleaning kits or instruction on how to clean the rifle.
 * 2) The M16 and 5.56x45mm cartridge was tested and approved with the use of a DuPont IMR8208M stick powder, that was switched to Olin Mathieson WC846 ball powder which produced much more fouling, that quickly jammed the action of the M16 (unless the gun was cleaned well and often).
 * 3) The M16 lacked a forward assist (rendering the rifle inoperable when it jammed).
 * 4) The M16 lacked a chromed barrel and chamber, causing corrosion problem, contributing to case swelling and extraction failures. (This was considered the most severe problem and required extreme measures to clear, such as inserting the cleaning-rod down the barrel and knocking the spent cartridge out.)"



When these issues were addressed and corrected by the M16A1, the reliability problems decreased greatly. According to a 1968 Department of Army report, the M16A1 rifle achieved widespread acceptance by U.S. troops in Vietnam. "Most men armed with the M16 in Vietnam rated this rifle's performance high, however, many men entertained some misgivings about the M16's reliability. When asked what weapon they preferred to carry in combat, 85 percent indicated that they wanted either the M16 or its submachine gun version, the XM177E2 . (The M14 was preferred by 15 percent, while less than one percent wished to carry either the Stoner rifle, the AK-47, the carbine or a pistol.)" In March 1970, the "President’s Blue Ribbon Defense Panel" concluded that the issuance of the M16 saved the lives of 20,000 U.S. servicemen during the Vietnam War, who would have otherwise died had the M14 remained in service. However the M16 rifle's reputation continues to suffer.

After the introduction of the M4 Carbine, it was found that the shorter barrel length of 14.5 inches also has a negative effect on reliability, as the gas port is located closer to the chamber than the gas port of the standard length M16 rifle: 7.5 inches instead of the 13 inches. This affects the M4’s timing and increases the amount of stress and heat on the critical components, thereby reducing reliability. In a 2002 assessment the USMC found that the M4 malfunctioned three times more often than the M16A4. Thereafter, the Army and Colt worked to make modifications to the M4 in order to address the problems found. In tests conducted in 2005 and 2006 the Army found that on average, the new M4s and M16s fired approximately 5,000 rounds between stoppages.

The newest version of the M16 in U.S. service is the HK416  which uses a proprietary gas system derived from the HK G36, replacing the direct impingement gas system used by the standard M16/M4. The HK system uses a short-stroke gas piston driving an operating rod to force the bolt carrier to the rear. This design prevents combustion gases from entering the weapon's interior, a shortcoming with direct impingement systems. The reduction in heat and fouling of the bolt carrier group increases the reliability of the weapon and extends the interval between stoppages. The short-stroke gas piston require less maintenance and cleaning. It reduces operator cleaning time and stress on critical components. "Improving the service interval requirements provides a major benefit to soldiers that may not have the ability or opportunity to thoroughly clean their rifle. Also, the design of the external gas piston system is less susceptible to build up of other contaminants in extreme environments." During factory tests the HK416 fired 10,000 rounds in full-auto without malfunctioning.

Magazines
"Magazines are one of the most important elements of any firearm design. They are responsible for the feeding portion of the cycle of operation. Even in the most proven arm that reliably extracts and ejects, the magazine has to be 100-percent reliable for it to consistently feed properly."

The AK-47’s 30-round magazines have a pronounced curve that allows them to smoothly feed ammunition into the chamber. Their heavy steel construction combined with "feed-lips" (the surfaces at the top of the magazine that control the angle at which the cartridge enters the chamber) machined from a single steel billet makes them highly resistant to damage. These magazines are so strong that "Soldiers have been known to use their mags as hammers, and even bottle openers." This makes the AK-47 magazine more reliable, although heavier than U.S. and NATO magazines. The early slab-sided steel AK-47 magazines weigh .43 kg empty. The later steel AKM magazines had lighter sheet-metal bodies with prominent reinforcing ribs weighing .33 kg empty. The current issue steel-reinforced plastic magazines are even lighter, weighing .25 kg empty. Early steel AK-47 magazines are 9.75 inches long, and the later ribbed steel AKM and newer plastic magazines are about an inch shorter.

The M16's magazine was meant to be a lightweight, disposable item. As such, it is made of pressed/stamped aluminum and was not designed to be durable. Therefore, it is easier to damage than an AK-47 magazine and the feed lips are proportionally weaker when compared to the AK-47. The M16 originally used a 20-round magazine which was later replaced by a bent 30-round design. As a result, the magazine follower tends to rock or tilt, causing malfunctions. Many non-U.S. and commercial magazines have been developed to effectively mitigate these shortcomings (e.g. H&K's all-stainless-steel magazine, Magpul's polymer P-MAG, etc.). In 2009, the U.S. Military began fielding an "improved magazine" identified by a tan-colored follower. "The new follower incorporates an extended rear leg and modified bullet protrusion for improved round stacking and orientation. The self-leveling/anti-tilt follower minimizes jamming while a wider spring coil profile creates even force distribution. The performance gains have not added weight or cost to the magazines." Standard USGI aluminum 30 round M16 magazines weigh .11 kg empty and are 7.1 inches long. The newer plastic magazines are about a half inch longer. And, the newer steel magazines are about a half inch longer and 4 ounces heavier.

Service life
The AK-47 and its variants are made in dozens of countries, with “quality ranging from finely engineered weapons to pieces of questionable workmanship.” As a result, the AK-47 has a service/system life of approximately 6,000, to 10,000, to 15,000 rounds. The AK-47 was designed to be a cheap, simple, easy to manufacture assault rifle, perfectly matching Soviet military doctrine that treats equipment and weapons as disposable items. As units are often deployed without adequate logistical support and dependent on “battlefield cannibalization” for resupply, it is actually more cost-effective to replace rather than repair weapons.

The M16 and its variants are made by dozens of manufactures around the world, to the highest standards "the goal of which is to ensure that products designed for military use meet the necessary requirements with regard to quality, durability, ruggedness, commonality, interchangeability, total cost of ownership, logistics and other military and defense-related objectives." The M16's barrel life is approximately 15,000 rounds for standard issue M16A4s and M4s. Cold hammer forged steel barrels such as those used on the HK416 have service life of 20,000 to 50,000 rounds depending on the intensity of use. A badly worn M16 barrel will cause the bullets to tumble in flight. However, the M16’s upper receiver/barrel may be swapped out in a matter of seconds, without the use of tools, simply by pushing out two pins. The M16 was designed to be a serviceable assault rifle, perfectly matching American military doctrine where units are resupplied on a continuous basis, and are expected to perform most of their own maintenance and repairs in the field. As such, American units are well supplied and are quickly provided with whatever spare-parts they need by their logistical support systems.

Both the AK-47 and the M16 have small parts and springs that need to be replaced every few thousand rounds.

Rifle evaluation study
The following Summary has been taken directly from the "Rifle Evaluation Study", United States Army, Combat Development Command, ADA046961, 20 Dec 1962. Additional information can be found in "Rifle Evaluation Study", United States Army, Infantry Combat Developments Agency, ADA050268, 10 Dec 1962".

Note: This is the first time that the United States Army compared the AR-15/M16 and the AK-47.

Night firing

The AR-15 was not equipped with any flash suppressor during the conduct of this test. Also, there was only a small amount of ammunition available for use in the AK-47. As a result, the night firing capability of the both the AR-15 and AK-47 were not properly tested. In a subsequent test at Fort Benning an AR-15 equipped with a flash suppressor was tested against both the M14 and the AK-47. The AK-47 was not equipped with a flash suppressor.

Further information

 * "Tales of the gun: The AK-47", History Channel documentary
 * "Tales of the gun: The M-16", History Channel documentary
 * "Great Battles: AK-47 vs M16", Military Channel documentary