Friday, April 29, 2011

History and Development of the Assault Rifle - VI

In our last post, we studied some of the history of the M16's predecessor, the AR-15. Where we left off was right at the end of development of the AR-15 by the Armalite Corporation. At this point, Armalite's parent company, Fairchild Aviation, decided that it had spent too much money on development expenses and wanted to get out of the firearms business. Hence, they sold the production rights to the Colt Firearms Company in December 1959, for $75,000 cash and 4.5% royalty on every unit manufactured. Shortly after this, Eugene Stoner left Armalite and began to work as a consultant for Colt.

Meanwhile, an USAF General, Curtis LeMay, witnessed a demonstration of the AR-15 in mid 1960 and became a proponent of the new weapon. Therefore, in 1961, he requested an order of 80,000 units for use by the Air Force. At that time, the US military was generally using the M14 rifle which fires a 7.62x51 mm. NATO cartridge. Hence, President John F. Kennedy, on the advice of US Army General Maxwell Taylor, stopped the AR-15 request on the grounds that having two different calibers within different military branches was a bad idea. However, another US government agency sent a batch of the new AR-15 rifles to South Vietnam, where it met with widespread praise by its users.

President Kennedy had appointed Mr. Robert McNamara as the Secretary of Defense at this point. Mr. McNamara was a former Ford Motor Company executive, who had risen up the ranks in Ford, becoming the first non-member of Henry Ford's family to become the president of the company. He had built his reputation by stopping Ford's losses in the late 40s and 50s by bringing in modern organization, management control and planning systems and was a big proponent of efficiency. Mr. McNamara started to push the various branches of the US military to adopt some common weapons, vehicles and aircraft to cut down costs (He was famously known as "Mac the Knife" in the Pentagon, for his cost-cutting measures). Now, after the enthusiastic reports about the AR-15 from South Vietnam, Mr. McNamara had to decide whether to believe the Pentagon's decision on sticking with the M14 or going with the positively glowing reports from South Vietnam about the new AR-15.

So he ordered Secretary of the Army, Cyrus Vance, to conduct tests between the M14, the AR-15 and the AK-47. The test results showed that the Army favored the existing M14, but then subsequent investigation showed that the testing methods were biased by the testers to favor the M14. In the end, Mr. McNamara ordered M14 production to stop in January 1963 because he determined that only the AR-15 could serve the needs of all branches of the US military. This was at a time when 5.56x45 mm. ammunition was not available widely, so the US Army tried to resist the change to the new rifle. The US Army also conducted a series of tests and wanted a few improvements done to the weapon:

  • Adding a chrome lining the inside of the barrel and the firing chamber in order to resist corrosion and wear and tear.
  • Adding a forward assist lever to push the rifle bolt into battery, in the event that a cartridge could not load into the chamber correctly due to corrosion or dirt.
  • Cleaning kits for the rifles.
Colt insisted that the design was self-cleaning and needed no maintenance and in order to cut costs, the first versions of the new rifle were released with no cleaning kits or chrome lining. Colt and the US Air Force also didn't want to add the forward assist lever, because it added an additional $4.50 to the cost of each rifle, but the US Army insisted upon this change. In the end, Colt decided to produce two versions, a US Airforce version called the M16, which has no forward-assist lever and another version, called the XM16E1, with the forward assist lever, for the other military branches. The XM16E1 was renamed as the M16A1 by the US Army. In November 1963, Mr. McNamara approved the US Army's order for 85,000 M16A1s for the US Army and an additional 19,000 M16 models for the US Air Force.

The M16A1 was sent to equip US troops in Vietnam, in 1965. Almost immediately, reports of jamming issues and malfunctions began to emerge. In several cases, dead US troops were found with jammed M16A1 rifles. A Congressional investigation was launched and the key culprit emerged -- it was the propellant used for the cartridges. The original cartridges used during the evaluation tests were manufactured by DuPont and used nitrocellulose based powder. However, these cartridges could not be profitably mass-produced and their propulsive force was just a bit below the desired specifications, when used in arctic conditions. Hence, a new cartridge from Olin Matheson was used instead, which used a mixture of nitrocellulose and nitroglycerin. This new propellant caused dirtier residue than the propellant used in the original cartridges when the rifle was first evaluated. Due to the fact that the rifle came with no chrome lining or cleaning kit, build up of residue could cause jamming issues. The new cartridge also burned faster and therefore increased the rifle's firing rate from 850 to 1000 rounds per minute, which caused extra stress on the rifle's springs.

Once the issues were identified, the US military quickly added chrome lining and also added a buffer system to reduce the firing rate to 650-850 rounds per minute. Cleaning kits and maintenance instructions were also issued and the rifle's failure rate immediately dropped. However, the early reliability issues gave this rifle a bad reputation in the beginning, and this bad reputation continued to dog the M16 for some years afterwards, even after the issues were all fixed. By 1968 though, the rifle began to gain popularity from US soldiers. A 1968 survey among 2100 US soldiers showed that only 38 individuals had wanted to replace the M16 with another weapon and of those 38 people, 35 of them had wanted the CAR-15, a carbine version of the M16!

Other NATO countries also wanted to share commonality with US military firearms and hence, they all began to adopt the 5.56x45 mm. cartridge. 

In the next post, we will study the development and insight into the design of the various M16 variants that followed the M16A1 model.

Monday, April 18, 2011

History and Development of the Assault Rifle - V

In the last few posts, we have been studying the developments of the AK rifle family designed in the Soviet Union. In the next few posts, we will study the development of the M16 assault rifle in the US.

We start our study around 1948, right after the end of World War II. An official US Army historian, Colonel (later Brigadier General) S.L.A ("Slam") Marshall was beginning to study the effects of combat on men and eventually authored several books on the subject. One of the most well known books was titled Men Against Fire, in which he claimed that during World War II, when US soldiers who were engaged in direct combat, 75% of them never fired their weapon directly at an enemy even when they were in combat. Per his research, there appeared to be a deep reluctance to kill another human being even at the risk of being killed. While some of SLA Marshall's research methods and conclusions were questioned much later on, in the 1950s and 1960s, he could do no wrong and was regarded as the ultimate authority. Other studies by the US army showed that people armed with automatic weapons were more likely to fire them in combat, because they were less likely to think about the consequences of killing another human. Still other analysis by the US army determined that most infantry combat occurred at relatively close ranges and that the side with the most firepower tended to win most engagements. The number of casualties of the enemy was found to be directly proportional to the number of bullets fired.

All these studies pointed to the fact that infantry soldiers should be provided with automatic weapons. However, this meant that the soldiers would use up ammunition more rapidly and would need to carry more of it into combat. This meant that the size and weight of the ammunition would have to be reduced in order to avoid overburdening the soldier. A research team in the US Army's Aberdeen Proving Ground facility in Maryland, was tasked with researching the effects of smaller calibers. They found that a .223 caliber (5.56 mm.) bullet moving at higher velocities had the same effects as larger rifle rounds in many combat situations and requested further funding from the US military to perform more experiments.

At the time that the US army was experimenting with smaller calibers, a division of Fairchild Aviation called ArmaLite was formed in 1954, to investigate uses of new materials and new designs for the firearms industry. It was a very small company at that time and the ninth employee was a talented weapon designer and Marine, who had served during World War II, Mr. Eugene Stoner. They produced an innovative rifle for the 7.62x51 mm. NATO cartridge that was in use at that time, called the AR-10. The AR-10 had several new features that were later featured in the M16. It used a direct impingement gas-operated action, unlike other piston and cylinder driven firearms (such as the AK family) used at that time. The direct impingement action didn't have a moving piston and hence was lighter and easier to keep pointed on target, especially when firing in fully automatic mode. Another feature, which was borrowed from the German FG-42 and Johnson LMG was the idea of a straight-line stock (i.e. the rifle stock is in line with the barrel), which serves to reduce muzzle climb. Previously, rifles would have a bend in the stock, so that the sights would be at eye level, while the recoil could be transferred to the shoulder of the user. With the stock inline with the barrel, a lot of the muzzle climb is significantly reduced (read the article on muzzle-climb linked above for why) and therefore, Armalite increased the height of the sights to compensate and the rear sight was mounted as part of the carrying handle.  The receiver was hinged (a feature also found on the FN FAL), but unlike most other rifles, it was constructed of aluminum alloy, which made it lighter than other rifles of its class. The bolt locking mechanism was also innovative for its time. The AR-10 was much lighter, smaller and easier to control in automatic fire than any of its competitors. However, against the wishes of Eugene Stoner, the president of Armalite wanted the barrel to also be made of aluminum/steel composite, which made the rifle's barrel weaker. Hence, when they submitted it for army evaluation, it burst under a torture test and was rejected. Armalite quickly replaced the barrel with an all-steel model, but the damage was done and the US army rejected the rifle. However, the improved model was used by a number of other forces around the world.

Meanwhile, a US general named Willard Wyman received the funding request from the Aberdeen Proving Ground facility and he formed a team to develop .223 caliber (5.56 mm.) firearms for testing. The finalized requirement asked for a firearm capable of selective fire, to be under 6 pounds (2.7 kg.) when loaded with 20 rounds. The bullet had to penetrate a standard US steel helmet of that time period from 500 yards, while exceeding the wounding properties of a .30 carbine. General Wyman had also seen the AR-10 trials and was impressed by some of its innovative features, so he personally asked Armalite to design a weapon using the 5.56 mm. cartridge. The result was a scaled down AR-10 model called the AR-15:

AR-15 assault rifle. Click on image to enlarge. Public domain image.

The AR-15 entered the design competition and the weird thing was that it entered with very little competition, because the main competitor (Springfield Arms) did not feel like diverting resources because they wanted to concentrate on M14 production, which the US military was already using. The only other competitor was an entry from Winchester called the LMR.

During the testing, it was found that rainwater could accumulate in the AR-15's barrel (as well as in the Winchester's barrel), due to the smaller diameter and capillary action. When such a rifle was fired, it could cause the barrel and action to burst. See myth #3 for the reason why. History buffs may also like to read a declassified report of the issue. The rifle was not as accurate in arctic conditions either. However, its lightness and rate of fire meant that an 8 man team could have the same firepower as a 11 man team using the M14 rifle.

In the next post, we will look into the adoption of the AR-15 and how it morphed into the M16

Sunday, April 17, 2011

History and Development of the Assault Rifle - IV

In the last post, we studied the origins of the AK-47 and the beginning of the AKM. The AKM featured several improvements over the AK-47, mostly geared towards improving the production rate. In the initial AK-47 design, they had attempted to make the receiver out of stamped parts to speed up production, but the Soviets lacked the proper technology to do so and had issues with the resulting product. Hence, they resorted to machining the receiver from a block of metal, which was a slower process. However, in the 1950s, they used several captured German technicians to teach them metal stamping technology and hence the AKM featured a stamped receiver. Among the many improvements that the AKM had over the original AK-47:

  • Replacement of the milled receiver with a receiver made out of stamped sheet steel. Machining is a lot slower process than using a press to stamp parts. Hence, use of stamped parts made it much faster to produce AKMs.
  • Using rivets instead of welds on the receiver, in order to speed up production.
  • Improvements to barrel, gas ports etc. to speed up manufacturing and enhance reliability
  • Weight reduction of approximately 1 kg. (2.2. pounds)
  • Retains the chrome lined barrel and chamber of the AK-47 Type-2 variant, but the barrel is pressed and pinned to the receiver, instead of the AK-47 which has a threaded barrel that is screwed into the receiver.
  • The barrel is the first in the AK family to have a slant compensator to reduce rifle climb, when shooting in automatic mode.
  • Gas relief ports are moved forward to the gas block, instead of the gas tube.
  • Bolt carrier was lightened slightly. The wooden stocks were also hollowed out as well, in order to reduce more weight.
  • Sights on an AKM are calibrated to go up to 1000 meters, whereas AK-47s are only calibrated to go up to 800 meters.
  • Changes to the metal treatment applied. The AKM is parkerized instead of blued like the AK-47.
  • Uses modified spring and trigger assembly for better safety. The AKM fires in automatic mode only when the bolt is fully locked. The new trigger assembly also reduces "trigger bounce" and has a hammer release delay device to delay the release of the hammer by a few microseconds in automatic firing mode. The hammer release delay mechanism is sometimes incorrectly called a "rate reducer" by some people, but it doesn't appreciably change the cyclic rate of fire. Instead it allows the bolt group to settle in the forwardmost position after returning into the battery.
The Soviets made millions of AKMs and they weren't shy about handing out the plans to other co-operating countries, so that they could make their own as well. This is why AKMs are so widespread around the world.

AKM assault rifle. Click on image to enlarge. Public domain image.

The basic AKM design also has a number of variants. Some of these are:
  • AKMS - This is one of the commoner variants of the base AKM. The AKMS features a metal stock, which is foldable.
  • AKMP - This variation uses tritium front and rear sights for better visibility in low light conditions
  • AKML - This variant has a side mounting rail to mount a night vision device.
  • AKMLP - Same as AKML, but also has tritium sights as a backup.
  • AKMSP - Same as AKMS, but fitted with tritium sights
  • AKMSN and AKMSNP - Same as AKMS (i.e. foldable stock), but also has a side mounting rail to attach a night vision device. The AKMSNP version also has tritium sights.

Thursday, April 7, 2011

History and Development of the Assault Rifle - III

In this post, we will look at the history of one of the most famous assault rifles in history, the AK-47. The AK family is pretty widespread around the world these days, but there are widespread myths about its origins. The Soviet propaganda machine liked to portray that it was an original design entirely invented by a self-taught Russian peasant named Mikhail Kalashnikov. The real truth is actually somewhat different. We will study the history of this firearm in the following series of posts.

In the last post, we saw how the concept of the assault rifle was successfully used by the Germans. Their assault rifle was used against the Soviet Union with great success. The Soviets, in turn, analyzed some captured weapons and decided that it was a pretty good idea. Another major influence was the American M1 Garand rifle, which was also supplied to the Soviets in large quantities by the US and the Soviets decided that they must also have a reliable weapon that fires intermediate power cartridges. They quickly established a factory to manufacture 7.62x41 mm. ammunition, but needed a rifle to go with it. The initial requests for new rifle designs were sent to various Soviet bureaus in late 1943 and by the spring of 1944, at least ten designs were submitted by different groups. The Soviets adopted a design by one Mr. Sudayev and his design was called the AS-44. A limited run of the AS-44 was produced just after WW-II ended and the troops were generally happy with these weapons as they were better than what they had previously. However, the AS-44 was just too heavy and thus the Soviets opened another design competition in 1946.

Meanwhile, in a little known battle, called the Battle of Bryansk in 1942, a certain Russian T34 tank commander named Mikhail Kalashnikov was wounded in combat and made it to the hospital on foot, to receive medical treatment. During his recovery period, he vowed that he would make sure that his country would never be defeated again. While he was lying in bed, he overheard some other soldiers complaining about the quality of the Soviet rifles and his own experiences with the standard Soviet infantry rifles of that period also were similar. Hence, he began to design his own firearm, a sub-machine gun. While his sub-machine gun design was rejected because it was over-complex, his talents as a designer were noticed and he was reassigned to the Red Army's Small Arms Research division. Here, he designed a carbine, which was heavily influenced by the American M1 Garand  rifle's piston driven gas-operated system (if the reader looks at an AK, it uses a gas-operated system almost identical to the Garand, except that the AK has the gas tube mounted on top of the barrel whereas it is below the barrel in an M1 Garand.) While this carbine also was not successful, it was the basis of a new assault rifle that was submitted to the Soviet design competition of 1946, the AK-1 (otherwise known as the AK-46). There were 16 other competing designs originally, with the old AS-44 acting as the benchmark standard and after the first round of trials, the AK-46 was chosen along with entries by A.A. Demetyev (the AD-46 rifle) and F. Bulkin (AB-46 rifle). In the second round of trials, the AK-46 was actually rejected because it did not perform as well as its other rivals, but Mikhail Kalashnikov managed to pull enough strings in the selection committee to continue work on his design and submit a new entry for the next round of trials. He went back to the drawing board with his assistant, Alexandr Zaitsyev, and decided to incorporate design features from other weapons (including some from his competitors, the AB-46 and AD-46!). The design of the AK-46's gas operated systems was already heavily influenced by the M1 Garand and the idea of the long stroke piston attached to the bolt carrier and return spring design were lifted from the AB-46 and the idea of large clearances came from the AS-44 and the safety lever mechanism was from the John Browning designed Remington 8 etc.  The new design was dubbed the AK-47.

The other two designers were also given an opportunity to make design improvements for the next set of trials held in 1947. In the next round of trials, the F. Bulkin design (AB-47/TKB-415) was actually the most accurate of the three weapons and the AK-47 was last.  However, the AB-47 had issues with parts wearing out quickly and the AK-47 beat out the other two handily in tests for durability and reliability. The selection committee made the decision that it is better to have a not-so-accurate-but-durable-and-reliable firearm than wait for an indefinite period for an accurate-and-reliable weapon and hence the AK-47 was chosen over its two competitors. The first version of this was deployed to limited troops between 1947 and 1948.

Initially the design called for a stamped steel receiver pinned at the front, for quicker manufacturing time. However, Soviet machine technology was not advanced enough to do this reliably and there were a large number of rejected receivers. Hence, the decision was made to manufacture the receivers using various machining operations. This made the manufacturing processes slower, but at least they could make reliable receivers this way. Therefore the AK-47 Mark I featured a machined receiver.

Meanwhile, a designer named German A. Korobov began to make an improved assault rifle design himself. Korobov had actually submitted a bullpup assault rifle design (the TKB-408) for the original design competion of 1946, but it was rejected after the first round of testing. Nevertheless, he continued to experiment with other bullpup and traditional rifle designs. By 1952, he switched to using the lever-delayed blowback action invented by Hungarian designer, Paul Kiraly. This led to more accuracy and simpler production for his design. In 1955, the Soviets started another design competition and the improved Korobov design (TKB-517) was submitted to the competition.

Meanwhile, the AK guys were not sitting idle either. They recruited several captured German engineers, including the renowned Hugo Schmeisser (the designer of the StG44) and learned mass production techniques from them. Their new design submission for the 1955 competition was the AKM (AK Modernizirovanniy, the Russian word for "Modernized").

Believe it or not, the TKB-517 pretty much beat the AKM on almost all counts. It was more accurate (especially in full automatic mode), significantly lighter and about 1/3rd cheaper to manufacture. So why did the Soviets adopt the AKM then? Because the selection committee decided that since the troops were already familiar with the AK-47, it would not be a good idea to replace it with a firearm that uses an entirely new design. Hence, the less-reliable, but more familiar AKM beat out the more accurate, but new design, TKB-517.

In the next post, we will look at further developments of the AK-47.