The U.S. Army defines assault rifles as "short, compact, selective-fire weapons that fire a cartridge intermediate in power between submachine gun and rifle cartridges." In a strict definition, a firearm must have at least the following characteristics to be considered an assault rifle:It must be capable of selective fire.
It must have an intermediate-power cartridge: more power than a pistol but less than a standard rifle or battle rifle.
Its ammunition must be supplied from a detachable box magazine.
It must have an effective range of at least 300 metres (330 yards).
Rifles that meet most of these criteria, but not all, are technically not assault rifles, despite frequently being called such.
For example:Select-fire M2 Carbines are not assault rifles; their effective range is only 200 yards.
Select-fire rifles such as the FN FAL battle rifle are not assault rifles; they fire full-powered rifle cartridges.
Semi-automatic-only rifles like variants of the Colt AR-15 are not assault rifles; they do not have select-fire capabilities.
Semi-auto rifles with fixed magazines like the SKS are not assault rifles; they do not have detachable box magazines and are not capable of automatic fire.
Selective fire rifles like the Fedorov Avtomat which in hindsight could be classified as prototypical assault rifles. However, 6.5x50mm Arisaka is still very much a full-powered rifle cartridge, only slightly weaker than 7.62x51mm NATO.
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. They would soon develop a select-fire intermediate powered rifle combining the firepower of a submachine gun with the range and accuracy of a rifle.
The result was the Sturmgewehr 44, which the Germans produced in large numbers; approximately half a million were made. It fired a new and revolutionary intermediate powered cartridge, the 7.92×33mm Kurz. This new cartridge was developed by shortening the standard 7.92×57mm Mauser round and giving it a lighter 125-grain bullet, that limited range but allowed for more controllable automatic fire. A smaller lighter cartridge also allowed soldiers to carry more ammunition "to support the higher consumption rate of automatic fire."
The Sturmgewehr 44 features an inexpensive, easy-to-make, stamped steel design and a 30-round detachable box magazine. "This weapon was the prototype of all successful automatic rifles. Characteristically (and unlike previous rifles and the M-14) it had a straight stock with the barrel under the gas cylinder to reduce the turning moment of recoil of the rifle in the shoulder and thus help reduce the tendency of shots to climb in automatic fire. The barrel and overall length were shorter than a traditional rifle and it had a pistol grip to hold the weapon more securely in automatic fire. The principle of this weapon — the reduction of muzzle impulse to get usable automatic fire within the actual ranges of combat — 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 that most combat engagements occur 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 7.62×39mm 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 were 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 bi-pod, a stronger receiver, and a longer, heavier barrel 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. "Of the estimated 500 million ﬁrearms worldwide, approximately 100 million belong to the Kalashnikov family, three-quarters of which are AK-47s."
On the other hand, 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. At the time, the U.S. Army believed that the Sturmgewehr 44 was "intended in a general way to serve the same purpose as the U.S. carbine" and was in many ways inferior to the M1 carbine, and was of "little importance".
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. However, early experiments with select-fire versions of the M1 Garand proved disappointing. During the Korean War, the select-fire M2 Carbine largely replaced the submachine gun in US service and became the most widely used Carbine variant. However, combat experience suggested that the .30 Carbine round was under-powered. American weapons designers reached the same conclusion as the German and Soviet ones: 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 7.62×51mm 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 Heckler & Koch G3 rifles, as well as the FN MAG and Rheinmetall MG3 GPMGs.
The FN FAL is a 7.62×51mm NATO, selective fire, automatic rifle produced by the Belgian armaments manufacturer Fabrique Nationale de Herstal (FN). During the Cold War it was adopted by many North Atlantic Treaty Organization (NATO) countries, most notably with the British Commonwealth as the L1A1. It is one of the most widely used rifles in history, having been used by more than 90 countries. The FAL was predominantly chambered for the 7.62mm NATO round, and because of its prevalence and widespread use among the armed forces of many western nations during the Cold War it was nicknamed "The right arm of the Free World".
The Heckler & Koch G3 is a 7.62×51mm NATO, selective fire, automatic rifle produced by the German armament manufacturer Heckler & Koch GmbH (H&K) in collaboration with the Spanish state-owned design and development agency CETME (Centro de Estudios Técnicos de Materiales Especiales). The rifle proved successful in the export market, being adopted by the armed forces of over 60 countries. After WWII, German technicians involved in developing the Sturmgewehr 45, continued their research in France at CEAM. The StG45 mechanism was modified by Ludwig Vorgrimler and Theodor Löffler at the Mulhouse facility between 1946 and 1949. Vorgrimler later went to work at CETME in Spain and developed the line of CETME automatic rifles based on his improved Stg45 design. Germany eventually purchased the license for the CETME design and manufactured the Heckler & Koch G3 as well as an entire line of weapons built on the same system, one of the most famous being the MP5 SMG.
The first confrontations between the AK-47 and the M14 (assault rifle vs battle rifle) 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 ammunition to maintain fire superiority over the AK-47. And, while the M2 Carbine offered a high rate of fire, it was under-powered and ultimately outclassed by 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. "(The M16) was much lighter compared to the M14 it replaced, ultimately allowing Soldiers to carry more ammunition. The air-cooled, gas-operated, magazine-fed assault rifle was made of steel, aluminum alloy and composite plastics, truly cutting-edge for the time. Designed with full and semi-automatic capabilities, the weapon initially did not respond well to wet and dirty conditions, sometimes even jamming in combat. After a few minor modifications, the weapon gained in popularity among troops on the battlefield."
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 5.56×45mm NATO 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.
During the 1960s other countries would follow the Americans lead and begin to develop 5.56×45mm assault rifles, most notably Germany with the Heckler & Koch HK33. The HK33 was essentially a smaller 5.56mm version of the 7.62×51mm Heckler & Koch G3 rifle. As one of the first 5.56mm assault rifles on the market, it would go on to become one of the most widely distributed assault rifles. The HK33 featured a modular design with a wide range of accessories (telescoping butt-stocks, optics, bi-pods, etc.) that could be easily removed and arranged in a variety configurations.
"The AK-74 assault rifle was a Soviet answer to the US M16." The Soviet military realized that the M16 had better range and accuracy over the AKM, and that its lighter cartridge allows soldiers to carry more ammunition. Therefore, in 1967, the USSR issued an official requirement to replace the AKM and the 7.62×39mm cartridge. They soon began to develop the AK-74 and the 5.45×39mm cartridge. AK-74 production began in 1974, and it was unveiled in 1977, when it was carried by Soviet parachute troops during the annual Red Square parade. It would soon replace the AKM and become the standard Soviet infantry rifle. In 1979, the AK-74 saw combat for the first time in Afghanistan, where the lethality of the 5.45mm rounds led to the mujahadeen dubbing them "poison bullets."
In March 1970, the U.S. recommended that all NATO forces adopt the 5.56×45mm 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 assault rifle type weapons. A NATO standardization effort soon started and tests of various rounds were carried out starting in 1977. The U.S. offered the 5.56×45mm M193 round, but there were concerns about its penetration in the face of the wider introduction of body armor. In the end the Belgian 5.56×45mm 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 improved penetration (specifically, to consistently penetrate the side of a steel helmet at 600 meters).
Also during the 1970s, Finland, Israel, South Africa and Sweden introduced AK type assault rifles in 5.56×45mm. During the 1990s, Russia developed the AK-101 in 5.56×45mm NATO for the world export market. In addition, Bulgaria, Czechoslovakia, Hungary, Poland and Yugoslavia (i.e., Serbia) have also rechambered their locally produced assault rifles to 5.56mm NATO. The adoption of the 5.56mm NATO and the Russian 5.45×39mm cartridges cemented the worldwide trend toward small caliber, high velocity cartridges.
In 1977, Austria introduced the 5.56×45mm Steyr AUG bullpup rifle, often cited as the first successful bullpup rifle, finding service with the armed forces of over twenty countries. It was highly advanced for the 1970s, combining in the same weapon the bullpup configuration, a polymer housing, dual vertical grips, an optical sight as standard, and a modular design. Highly reliable, light, and accurate, the Steyr AUG showed clearly the potential of the bullpup layout. In 1978, France introduced the 5.56×45mm FAMAS bullpup rifle. In 1985, the British introduced the 5.56×45mm L85 bullpup rifle. In the late 1990s, Israel introduced the 5.56mm NATO Tavor TAR-21. In 1997, China's People's Liberation Army's adopted QBZ-95 in the new 5.8×42mm cartridge, which they claim is superior to the both 5.56×45mm and the 5.45×39mm. By the turn of the century, the bullpup assault rifle design had achieved worldwide acceptance.
The term assault rifle, when used in its proper context, militarily or by its specific functionality, has a generally accepted definition with the firearm manufacturing community. In more casual usage, the term assault weapon is sometimes conflated or confused with the term assault rifle.
In the United States "assault weapons" are usually defined in legislation as semi-automatic firearms that have certain features generally associated with military firearms, including assault rifles. The 1994 Federal Assault Weapons Ban, which expired on September 13, 2004, codified a definition of an assault weapon. It defined the rifle type of assault weapon as a semiautomatic firearm with the ability to accept a detachable magazine and two or more of the following:a folding or telescoping stock
a pistol grip that protrudes conspicuously beneath the action of the weapon
a bayonet mount
a flash suppressor or threaded barrel designed to accommodate a flash suppressor
a grenade launcher
Some states have passed more restrictive laws, with more inclusive definitions of assault weapons. One example is the NY SAFE Act, which changed the restriction to one or more (rather than two or more) of the above features, and expanded the restricted muzzle devices beyond just flash suppressors to include compensators and muzzle brakes.
Assault weapons legislation does not further restrict weapons capable of fully automatic fire, such as assault rifles and machine guns, which have been continuously and heavily regulated since the National Firearms Act of 1934 was passed. Subsequent laws such as the Gun Control Act of 1968 and the Firearm Owners Protection Act of 1986 also affected the importation and civilian ownership of fully automatic firearms, the latter fully prohibiting sales of newly manufactured machine guns to non-law enforcement or SOT (special occupational taxpayer) dealers.