In the 2008 film Wanted, mild-mannered office worker Wesley Gibson, played by James McAvoy, is inducted into a secret group of elite assassins known as The Fraternity, who keep the world in balance by eliminating those who threaten its safety. Among the superhuman skills Wesley learns is the ability to “curve” bullets by swinging his pistol as he fires, allowing him to hit targets hidden behind obstacles. While this makes for an awesome cinematic visual, is it actually possible to do this? Can you actually curve a bullet like a pitcher curves a baseball?

The short answer is no – at least, not in the way shown in Wanted, but there is a caveat we’ll get to in a bit. But for now, the reason has to do with plain old inertia. When an object is set in motion, it will travel in a straight line unless some force acts upon it. Thus, no matter how fast you swing your gun while firing, the bullet will fly in the same direction it was travelling the moment it left the barrel. Once in free flight, there are only two major forces that can affect a bullet’s trajectory: gravity and air resistance. Gravity, of course, pulls the bullet towards the centre of the earth, causing it to travel in a downward-arcing trajectory. Wind resistance, however – specifically from a crosswind – can cause a bullet’s trajectory to curve sideways. This is called windage, and the sights of nearly all rifles are designed to be adjustable to compensate for this effect. However, due to the high density, small surface area, and high velocity of most bullets, windage is only significant over long distances and would be useless for curving a bullet around, say, Angelina Jolie. Similarly, another force that can affect bullets – at least, modern, spin-stabilized ones – is the Magnus Effect, the same aerodynamic phenomenon causes golf balls to “slice”, baseballs to curve, and soccer balls (football to our non-American viewers) to “bend” into the net. However, for a cylindrical bullet spinning around its longitudinal axis, the Magnus Effect acts either upwards or downwards – not sideways. To achieve a sideways curve, a gun would need to fire a spherical projectile spinning around its vertical axis – but again, so high are the inertial forces compared to the aerodynamic forces acting on a bullet that this curve would be very gradual and only become apparent over long ranges. To make the curve more pronounced at short range, you must make the projectile much larger and far less dense – creating, essentially, a nerf gun.

Of course, there is a third way to make a bullet curve in flight: the Coriolis effect. Known to most people as the phenomenon that apparently makes toilets flush a different direction in the southern hemisphere (spoiler alert: no it doesn’t) in this case the Coriolis effect is the result of the earth rotating beneath a projectile as it flies, making it seem as though it is travelling along a curved trajectory. But once again, this effect only occurs over very long distances and is useless in a Wanted-type gunfight. So, in conclusion, there is no practical way to bend a regular bullet over the short distances depicted in Wanted. Sorry, all you would-be super assassins: you’ll just have to take out your targets the old-fashioned way.

“But wait”, I hear you saying, “If you can’t curve a bullet by swinging a gun around, what about bending the barrel to shoot around corners?” Well, as goofy as it may sound, this actually is possible, and has been tried several times throughout history. During the First World War, armies on both sides extensively experimented with so-called periscope rifles to allow soldiers to shoot over the rim of a trench without exposing themselves to enemy fire. These typically consisted of a wooden or metal frame holding a regular service rifle and fitted with a periscopic sight and various levers connected to the bolt and trigger to allow said rifle to be safely operated from below. But while this fits the technical definition of “shooting around corners”, none of these devices made use of a curved barrel to bend the bullet’s trajectory, though did result in some rather interesting guns. The first patent for a curved-barrel firearm would not appear until 1919, filed by inventor Alexander T. Fischer of Detroit, Michigan. Dubbed A Device for Oblique Firing, Fischer’s design included a periscopic sight so that firearms fitted with the system could be fired:

“…at an angle from that of the line of sight as is now practised. This improvement is especially desirable in airplane usage in war, as it enables the observer to shoot over the side of the airplane and direct his bullet to an object beneath him without being obliged to hold the fire arm in a vertical or nearly vertical position and without being exposed to fire from his adversary. Soldiers also by its use may fire over parapets without exposure to adverse fire.”

This description suggests that Fischer was naively ignorant with the realities of aerial combat, for by 1919 the days of aircraft observers firing at ground targets with regular rifles was long past. And unless the observer’s compartment was armoured – which few 1910s aircraft were – hiding behind its edge would make little difference to the gunner’s safety. And while Fischer’s invention was theoretically better suited to infantry use, there is no evidence a working example was ever built. It would not be until the 1940s that a working curved-barrel firearm was actually fielded by – who else – the Nazis.

Known as the krummlauf – literally “curved barrel” – this device was the brainchild of Hans Schaede of Düsseldorf weapons manufacturer Rheinmetall-Borsig, with development beginning in 1943. As it was believed that bending a regular barrel would impart too much stress on it and the bullet, the first prototypes used a curved piece of 20mm barrel as a “trough” to help guide the 8mm bullet around a corner. However, this did not work nearly as well as planned, and it was soon discovered that simply using a curved 8mm barrel actually worked much better. The curve still placed tremendous stress on the barrel extension, so relief holes were drilled to release some of the pressure. As the krummlauf was only intended for short-range use, the resulting loss of velocity and accuracy was not considered a major problem.

Several different versions of the krummlauf were developed, broadly divided into ‘I’ variants for infantry use and ‘P’ or panzer variants for use aboard armoured vehicles. 30º, 45º, 60º and 90º versions were designed, as well as special mountings for the MG-42 machine gun and the StG-44 assault rifle. (More on the fascinating history of assault rifles in the Bonus Facts in a bit.) The 90º ‘P’ krummlaufs were specifically designed for use in tank destroyers like the Porsche Elefant, which was not fitted with defensive machine guns. Mounted in a special swivelling cupola fitted with a periscope, an StG-44 fitted with a krummlauf allowed the vehicle crew to defend themselves against attacking infantry while keeping the weapon vertical, minimizing the space it occupied inside the hull. In the end, however, only the 30º ‘I’ variant for the StG-44 was produced in any significant numbers – and even then, of the 20,000 initially ordered, only around 500 ever made it into the field.

Intended for use in urban warfare, the ‘I’ krummlauf featured a 35 centimetre barrel, comprising a 10 cm straight section, a 14 cm curved section, and another 11 cm straight section. This clamped over the front sight and muzzle of the StG-44 using the same mount as the German Army’s standard schiessbecher grenade launching cup. While early on efforts were made to line up the rifling of the weapon and the krummlauf, this was eventually found to be unnecessary and production versions actually featured a short bored-out section between the muzzle of the weapon and the start of the curved barrel to allow the bullet to re-center itself. And to allow the infantryman to see what he was shooting at, the krummlauf was fitted with a periscopic mirror in a sheet-metal housing. This in turn featured a triangular shield to prevent gases from the barrel from clouding the optics.

Like many German “wunderwaffe,” the krummlauf arrived too late and in too few numbers to have any impact on the end of the war. However, the Allies took a keen interest in the odd-looking design, with both the Americans and Russians conducting extensive tests on captured examples. The results were something of a mixed bag. While comfortable to shoot and capable of achieving 35×35 centimetre grouping at a range of 100 metres when fired in semi-automatic mode, the 30º ‘I’ krummlauf became uncontrollable in fully-automatic fire, the sideways recoil spinning the shooter dangerously to the side. The powerful forces in the curved barrel also tended to tear the bullets into fragments, though this unintended shotgun effect was theoretically useful in close-quarters urban combat. However, these same forces also caused the barrel to very quickly wear out. Though originally designed to last 6,000 shots, in practice most krummlaufs failed after just a few hundred.

In his final report, Colonel H.A. Quinn of Aberdeen Proving Ground in Maryland concluded that:

“Despite the fact that the bent-barrel theory is in violation of accepted ideas on bullet delivery, it is believed to be worthy of extensive research and development. With the short length, large diameter, and short bearing of the 230-grain U.S. Caliber .45 bullet, various degrees of bent barrels might prove to be successful, and with reasonable control. With the 7.9mm Kurzpatronen bullet, it is believed that the 30-degree bend is practical. The 90-degree bend is apparently impractical.”

The Soviets came to similar conclusions, and produced experimental versions of the Mosin-Nagant 91/30 and AVS-36 rifles and the PPsH-41 submachine gun with 30º curved barrels. However, neither the U.S. nor the Red Army chose to pursue the idea any further.

But if curving a firearm’s barrel around a corner is impractical, why not just bend the whole firearm? This was the thinking Israeli Defense Forces Lieutenant Colonel and counter-terrorist expert Amos Golan when he created one of the most unique weapons currently in service: the CornerShot. Introduced in the year 2000, the CornerShot is not a weapon per se but rather a rifle-like chassis with a forward section designed to hold a standard service pistol like a Glock 17 or Beretta 92F. This section is hinged to allow the attached firearm to fire around corners, and incorporates a high-definition television camera connected to a screen on the rear of the device to allow the operator to see what they are shooting at. And if that weren’t bizarre enough, among the many accessories created for the CornerShot is the Kitty Corner Shot, a stuffed animal resembling a cat designed to be slipped over the muzzle of the pistol. The idea is that when the Kitty Corner Shot is pushed around a corner, it will distract the target just long enough for the CornerShot gunner to get them in their sights. And if you ask us, when someone starts coming up with ideas that unhinged, it is they, and not the bullets, that are truly going around the bend…

Bonus Fact:

Speaking of innovative weapons, what we now call assault rifles can trace their origins back to the Second World War. While that conflict is remembered for introducing advanced technologies like radar, jet aircraft, and nuclear weapons, the average infantryman went into WWII armed essentially the same weapon his parents had used in the last war: a bolt-action, manually-repeating rifle firing a full-power cartridge. The only major exception was the United States, which in 1936 became the first nation to issue a semi-automatic rifle – the M1 Garand – as its standard infantry weapon. But while such weapons were well-suited to shooting across no-man’s-land during the Great War or the South African Veldt during the Boer War, in the increasingly urban, close-quarters combat troops increasingly found themselves engaged in, bolt-action rifles quickly became something of a liability. Not only were they slow and awkward to operate – severely limiting the volume of fire that could be laid down – but the full-power cartridges they fired, great for precision shots over long distances, were grossly overpowered, with Army reports indicating that few combat engagements occurred at ranges over 300 metres. Such cartridges also made fully-automatic weapons all but uncontrollable when fired from the shoulder.

Thankfully, most armies had another class of weapon at their arsenal: the submachine gun. Developed at the end of the Great War for raiding and clearing trenches, submachine guns fired lower-recoil pistol-calibre ammunition and could deliver a murderous volume of fire at close quarters, making them ideal for urban combat. This advantage was exploited to great effect by the Soviet Red Army, who equipped entire infantry companies with PPsH-41 and 43 submachine guns for house-to-house fighting in cities like Stalingrad. But submachine guns were not a perfect solution, being inaccurate at ranges beyond a few dozen metres. Both the Soviets and the Germans quickly realized that this new kind of combat required a new kind of weapon, one which combined the volume of fire and full-auto controllability of a submachine gun with the accuracy of a rifle – at least over moderate ranges.

Interestingly, both nations approached the same problem from opposite ends. Unlike most armies, the tactical structure of the German Wehrmacht was organized not around the rifleman, but rather the machine gun squad, with rifle-carrying infantry playing a supporting role. This is a major reason army planners chose to retain the Great War-era Mauser 1898-pattern bolt-action rifle rather than adopt a more modern semi-automatic infantry weapon. But while this arrangement worked well during the Blitzkrieg campaigns of 1939, 1940, and 1941, it proved less effective in 1943 as the Wehrmacht found itself in full-on retreat following the disaster at Stalingrad. Though the German MG 34 and MG 42 machine guns could lay down an impressive volume of fire, they required extensive setup before they could be brought to bear – something that was difficult to do while retreating. German industry thus set about designing a more compact, man-portable machine gun that could be more easily used on the retreat.

Fortuitously, the basic elements for such a weapon were already in development. In 1938, the Polte Ammunition Works in Magdeburg designed a new kind of ammunition, designated the 7.92x33mm Kurz or “short.” This was essentially a cut-down version of the standard full-power 7.92x 57mm Mauser cartridge used in German bolt-action rifles and machine guns, with a shorter case and lighter bullet. This provided a balance between recoil and accuracy, allowing an infantryman to lay down controllable automatic fire from the shoulder while still being able to accurately hit targets out to 300 metres. In 1940 the German government issued contracts to firms Haenel and Walther to produce prototypes of a rifle to fire the new Kurz cartridge, to be designated the Maschinenkarabiner or “Machine Carbine” 42. Both companies produced similar weapons, which looked unlike anything that had come before. Both were gas-operated, built of lightweight and inexpensive welded steel stampings, and featured an inline shoulder stock, low-slung barrel to reduce muzzle climb, and a long, curved 30-round detachable box magazine. Both companies’ prototypes were extensively tested at the Kummersdorf proving grounds in December 1940, and the results were…less than impressive, with the weapons suffering a large number of jams, burst barrels and other failures. Undaunted, Walther and Haenel continued to refine their designs, and in April 1942 the Haenel weapon was judged reliable enough for combat trials, first seeing service on the Eastern Front, south of Leningrad.

The reaction of the first troops to use the new weapon was overwhelmingly positive, and they requested that more MKb 42s be sent to the front immediately. Unfortunately, the entire program suddenly fell victim to that greatest of enemies to the German war effort: Adolf Hitler, who ordered all new rifle development programs suspended. The reason for this decision is hotly debated among historians, with some arguing that Hitler, having been a soldier in the Great War himself, was suspicious of new technology and believed that the standard KAR98K bolt-action rifle was perfectly adequate for the German infantryman’s needs. Others, however, claim that his decision was a far more pragmatic one. German forces had lost vast quantities of rifles and other weapons during the retreat from Stalingrad, greatly straining the capacity of German industry to replace them. Introducing a new pattern of rifle, which required brand-new tooling and manufacturing facilities, would only make the situation worse and result in too few new rifles being produced to have any significant impact on the war effort. Hitler thus limited research and development efforts to upgraded models of submachine guns.

Believing they had a winning weapon on their hands, Haenel made the bold decision to go behind the Führer’s back and continue development of the Mkb 42 under the designation Maschinenpistole or “Machine Pistol” 43. In order to address the issue of manufacturing capacity, Haenel attempted to develop the MP 43 into a complete replacement for the KAR98K, fitting it with a grenade launching attachment, mounts for telescopic sights, and a bayonet lug. Unfortunately, the rifle proved fundamentally unsuited to sniping, bayonet fighting, or grenade launching, and it was reluctantly decided that the MP43 could only ever supplement the KAR98K, not replace it. In March 1943, Hitler discovered Haenel’s deception and ordered the project shut down once again. However, he was eventually persuaded to allow development to continue on an evaluation basis only. But the results of early trials proved so promising that Hitler approved the weapon for mass-production, the first examples entering combat in October 1943. Once again the reaction from front-line soldiers was overwhelmingly positive- so much so that when Hitler asked his Eastern Front generals in July 1944 what they most needed, one general immediately exclaimed “more of those new rifles!” Hitler soon warmed to the MP 43 concept, and recognizing the propaganda value of this new weapon, requested that it be given a new name: Sturmgewehr, or “Assault Rifle.” Nearly 426,000 StG 44 rifles were produced by the end of the war, and while they proved extremely effective in combat, by the time they entered service the war for Germany was already lost, and the new weapon had little to no impact on the final outcome of the conflict. However, the basic concept of a select-fire rifle firing an intermediate cartridge – as well as the name “assault rifle” – was to have a major impact on the future of firearms design.

Meanwhile, a similar development was taking place in the Soviet Union. Recognizing, as the Germans had, the need for a cartridge halfway between a pistol and rifle in power, in 1943 the Soviet OKB-44 design bureau developed the intermediate 7.62x39mm cartridge for use in a planned family of new infantry weapons, including a semi-automatic rifle, an automatic rifle, and a light machine gun. The cartridge, along with the semi-automatic SKS rifle designed by Sergei Simonov, first entered combat in limited numbers in 1945 during the final battles against Nazi Germany. The round performed well, and in 1949 the SKS was officially adopted as the Red Army’s standard rifle, alongside the RPD light machine gun firing the same round. However, the SKS would prove extremely short-lived in front-line service, thanks to the development of a weapon that would go on to become legendary.

In October 1941, tank commander Mikhail Kalashnikov was recovering in hospital from shoulder wounds received during the Battle of Bryansk. With plenty of time on his hands, Kalashnikov decided to solve what he saw as a major deficiency in Soviet armaments and designed a new type of submachine gun for the Red Army:

“I was in the hospital, and a soldier in the bed beside me asked: ‘Why do our soldiers have only one rifle for two or three of our men, when the Germans have automatics?’ So I designed one. I was a soldier, and I created a machine gun for a soldier.”

While Kalashnikov’s submachine gun was not accepted into service, his talent as a designer was recognized and he was reassigned to the Red Army’s Central Scientific Development Firing Range for Rifle Firearms of the Chief Artillery Directorate. In 1944 Kalashnikov became aware of the 7.62x39mm intermediate cartridge and redesigned his submachine gun to accommodate it. The resulting weapon looked very similar to the German StG 44, with an inline stock, low-slung barrel, and curved 30-round magazine. Whether Kalashnikov was directly influenced by the German weapon is debatable, with most historians attributing the similarities to a case of convergent design – that is, of two designers coming up with similar solutions to the same problem. Indeed, the operating mechanism of the two rifles is quite different, the StG 44 using a tipping bolt and the Kalashnikov a rotating bolt. However, it is worth noting while the Germans were trying to create a machine gun that could be used at shorter ranges, Kalashnikov was trying to create a submachine gun that could be used at longer ranges.

In 1946 Kalashnikov entered his design into a competition for a new infantry automatic rifle, which it eventually won. In 1947, the weapon was approved for service under the designation Avtomat Kalashnikova – or “Kalashnikov’s Automatic Rifle” – 1947, better known as the AK-47. Trials of the new rifle began in 1948, and in 1949 the AK-47 was adopted as the Red Army’s standard rifle, replacing the SKS after barely a year in service. The AK family of rifles would go on to become the most successful and widely-produced firearms in history, renowned for their ruggedness, reliability, and ease of use. Millions were exported around the world by the Soviet Union, China, and other communist states, and can be found in war zones worldwide to this day. It is important to note here that while the weapon is popularly referred to as the “AK-47,” this designation technically applies to the first three patterns of the rifle. While the first AK-47 featured stamped steel construction like the StG 44, this proved unreliable and was quickly replaced by machined steel construction for the Type 2 in 1951 and Type 3 in 1954. Then, in 1959, Soviet manufacturers finally perfected the stamped-steel technology and introduced the Modernized AK or AKM. This is the AK most commonly encountered around the world, the original “AK-47” patterns being extremely rare.

Yet despite the success of the StG 44 and the AK, it took several decades for the assault rifle concept to catch on in the West. American infantry doctrine had long emphasized individual marksmanship and firing accurate aimed shots over long distances over suppressing fire, and despite the lessons of urban close-combat combat during WWII, the United States was reluctant to adopt an intermediate cartridge. In 1954 the U.S. pressured the newly-formed North Atlantic Treaty Organization or NATO into adopting the full-power 7.62×51 or .308 calibre cartridge as its infantry standard. This decision forced many NATO countries to abandon advanced assault rifle projects and adopt so-called “battle rifles” firing full-power cartridges, such as the Belgian FN-FAL, German G3, and American M14, which was essentially an M1 Garand with a detachable box magazine and select-fire capability. Unfortunately, these rifles proved less than ideal, the full-power .308 cartridge making them nigh-uncontrollable in full-automatic fire. This led many countries like the UK to delete the full-automatic capability from their battle rifles altogether.

The deficiencies of the battle rifle concept became glaringly obvious as the United States entered the Vietnam War, where the bulky, wood-stocked M14 proved prone to snagging in heavy brush and warping in the tropical humidity. By contrast, the Chinese-supplied SKSs and AKs used by the Viet Cong and North Vietnamese Army proved ideally suited to jungle warfare, being light, compact, reliable, and capable of controlled automatic fire. It quickly became clear to U.S. Commanders that an American answer to the AK was desperately needed. Thankfully, just such a weapon was already in development.

In 1954, Richard Boutelle, president of the Fairchild Engine and Airplane Corporation, created the ArmaLite division to explore the use of aluminium and other aerospace materials in firearms design. The division’s first success came that same year when it designed the lightweight folding AR-5 and AR-7 survival rifles for use by U.S. aircrew shot down behind enemy lines. In 1957, ArmaLite was invited to enter the competition for a new U.S. Forces rifle to replace the WWII-era M1 Garand, and to this end designer Eugene Stoner produced the AR-10, a lightweight aluminium-bodied rifle firing the 7.62x51mm NATO round. While the AR-10 would ultimately lose out to the M14, that same year General Willard G. Wyman, commander of the U.S. Army Continental Command, put out a request for a lightweight automatic rifle to fire the newly-developed 5.56x45mm or .223 calibre intermediate cartridge. Stoner scaled down the AR-10 design to create a new rifle called the AR-15, which after extensive trials and conversion to fully-automatic capability was adopted into U.S. service in 1964 as the M16. While the lightweight, space-age weapon was initially disparaged by troops as the “Mattel Rifle”, the M16 quickly proved its worth in the jungles of Vietnam, and Eugene Stoner’s AR system has formed the basis for all standard U.S. military service rifles to the present day. The rifle also set the trend for modern assault rifles, the 5.56x45mm cartridge being flatter-shooting and more lightweight than the Russian 7.62×54, the latter feature allowing an infantryman to carry more ammunition. As a result, in 1974 the Soviet Union replaced the AKM with the AK74 firing the broadly similar 5.45x39mm cartridge. And in 1980 NATO adopted 5.56x45mm as its infantry standard, replacing the full-power 7.62×51.

And if you’re now wondering what actually makes something an assault rifle according to the U.S. Army definition, to be classified as an assault rifle a firearm must have three basic characteristics embodied in the original StG 44 and AK-47: 1) it must fire an intermediate cartridge with an effective range of at least 300 metres; 2) it must have select-fire capability – that is, the ability to fire in fully-automatic mode; and 3) it must have a high-capacity detachable box magazine. By this definition, most civilian versions of the widely demonized AR-15 are not, in fact assault rifles, for while these rifles are designed to fire an intermediate cartridge and can be fitted with large capacity magazines, the AR-15 is, by definition, a semi-automatic firearm. Furthermore, “AR” does not stand for “Assault Rifle,” as is widely believed, but rather “Armalite Rifle.” Similarly, any firearm lacking one or more of the above characteristics cannot be classified as an assault rifle. For example, the original M14 has a detachable high capacity magazine and select-fire capability, but fires a full-power rifle cartridge; while the SKS, despite firing an intermediate cartridge, has only a 10-round fixed magazine and no select-fire capability.

Nor should “Assault Rifles” be confused with “Assault Weapons,” the latter being neither a technical or military term but rather a political one.