Real-life Small Arms
Guns, guns, guns! We all have our personal opinions as to whether we should be keeping stockpiles of them in our basements, letting kids use them before they're old enough to drive, or imposing rules of conduct on gun owners (eg. making them take safety courses or lock up their ammo), but there can be no doubt whatsoever that they have revolutionized warfare, and let's face it: there's something enticing and glamorous about them (c'mon, admit it; even if you're a hard-line gun control advocate, there's something very cool about those gleaming metal guns).
There are a bewildering variety of military guns being made around the world, but most of them can be categorized thusly (keep in mind that these brief descriptions were written to be concise rather than comprehensive; I am attempting to provide some basic background for a sci-fi site, not the definitive history of military firearms).
Handguns
The
handgun, also known as the pistol, is a small handheld single-fire
weapon with an ammunition capacity of 5-15 shots and which can be
easily carried in a holster. It is optimized for infrequent,
low-intensity close-quarters combat, and it has limited accuracy,
being effective only within a dozen metres or so in the hands of
anyone but an unusually skilled marksman. The large (9-11mm) rounds
can cause extensive tissue damage but have poor armour penetration, since
their muzzle velocity is barely supersonic. However, this can
paradoxically be an advantage in certain situations; a police
officer, for example, is charged with the responsibility of limiting
collateral damage (eg. civilian casualties), and that would be much
more difficult if his weapon was capable of easily punching through
masonry walls. Handguns are small enough to carry virtually anywhere
on one's person, they are inexpensive enough to build in huge
numbers, and they are convenient because a loaded handgun can be
carried safely, deployed quickly, and concealed if necessary. It is
for these reasons that handguns are often found in the hands of
police officers as well as military personnel who aren't expected to
engage in intense combat, such as guards, officers, MP's, and
aircraft crews.
Sub-machine Guns
The SMG is a small automatic weapon whose range and accuracy fall somewhere between handguns and assault rifles, thus optimizing it for close-range combat. The accuracy of an SMG is much greater than that of a normal handgun, but it is still limited by its short length and its chattering recoil. If fired with one hand it is basically random, and even if held with both hands, its accuracy is still very limited unless the extendable shoulder stock and sights are used. However, its sheer rate of fire generally makes up for this limitation at close range. The legendary Uzi, for example, can fire more than ten rounds per second but its effective range is only 50-70 metres. However, when the shoulder stock is used, a good SMG can hit targets at more than 150 metres. Some SMGs such as the Heckler & Koch MP5 can be equipped with telescopic sights or even laser "red dot" sights, which are particularly useful for commandos using single-shot mode. In combat, a scope on such a weapon is used not for very long-range sniping but to hit specific "critical targets" at the beginning of an assault, such as enemy officers, men with machine guns, radio operators, etc.
SMGs are highly effective in close quarters, particularly in urban fighting where they are ideal for the euphemistically named job of "clearing out a room". They are less expensive than assault rifles, their limited penetrating power makes them suitable for police, bodyguard, or anti-terrorist work, and they can be so compact that some of them approach the size and convenience of handguns, thus meriting the term "machine pistol". It is for these reasons that SMGs are popular with anti-terrorist squads, SWAT teams, paramilitary organizations, commandos, and non-infantry military personnel such as tank crews or truck drivers, who want the firepower of an automatic weapon without the bulk (and expense) of an assault rifle.
The SMG category is fairly broad. The two guns pictured above are both classified as SMGs (in the Heckler & Koch MP5 family), but while the one on the left (an MP5-N) was designed for the U.S. Navy SEALs with a usable foregrip and an extendable shoulder stock, the one on the right (an MP5K) is a very small, special-purpose weapon designed for extreme close-quarters combat (don't let the different picture scales fool you; it's much smaller than the gun on the left). It is meant to be stabilized in a special shoulder sling, and H&K actually has special training courses specifically for this weapon. Both guns use 9mm ammunition.
As an historical aside, the SMG has even been used as an infantry weapon in the past; in fact, the WW2 Russian army equipped entire infantry divisions with them. They used these weapons very effectively by taking advantage of the urban environments and artillery-devastated landscapes that were typical of combat terrain in that theatre, particularly in the heavy urban fighting of the city sieges. Long-range fields of fire were virtually non-existent in those situations, so it was a highly effective tactic to approach the enemy under covering fire and engage him at arm's length. Furthermore, the indoor combat of urban fighting made the length of a rifle a potentially deadly inconvenience (try to imagine swinging a long assault rifle around while fighting in stairwells and corridors, or bursting into rooms). Since the SMG does not require a long, tight tolerance rifled barrel, it can be made for much less money than the full-fledged assault rifle or machine gun. Some famous SMGs such as the British Sten gun were made from stamped metal and so enormous quantities could be manufactured very quickly, even under duress. This made the SMG a good fit for Britain and Russia in WW2, both of whom were attempting to mobilize and expand their armies while being bombed into the Stone Age by the Nazis.
After WW2, SMGs fell out of favour with most armies due to the increasing popularity of small calibre weapons such as carbines and assault rifles. Russia was still making SMGs in the 1990's, and Israel has produced huge numbers of Uzis for their military forces, but the logistical benefits of standardization on 7.62mm and 5.56mm ammunition seem to limit the chances that the SMG will return as a widely used military weapon. Moreover, the development of low-penetration 5.56mm ammunition hints at the possibility that carbines may begin to usurp some of the specialist roles where the SMG has traditionally been untouchable.
Carbines
Since
SMGs are generally designed to fire low-velocity 9mm or .45"
calibre pistol rounds, there are limits to their performance,
particularly with respect to armour penetration. If someone requires a
weapon with greater effective range or penetration, there is an alternative:
the carbine. A carbine is distinguished from an SMG primarily by its use
of a rifle cartridge (it is basically a rifle with a shortened barrel), and there
can also be differences in operating mechanism. The principal SMG
attributes of low cost, good short-range firepower, and midrange
accuracy are valuable, but against a target wearing body armour, a
carbine provides many of the same attributes while also providing the
benefits of the high-velocity rifle cartridge.
For example, the HK53 pictured at right looks remarkably similar to the MP5-N SMG made by the same manufacturer, being only 2 inches longer. However, it uses high-velocity 5.56mm rifle ammunition rather than low-velocity 9mm pistol ammunition, and it can pierce a steel helmet at 200 metres. Another famous example is the WW2-era American M1 carbine. Today, the US Army's carbine is the M4, which is a shortened version of the M16 and which can be equipped with many of the same accessories, such as a grenade launcher, night-sight scope, etc. The short barrel of a carbine limits its accuracy and therefore its effective range in comparison to a full-fledged rifle, but it is compact and lethal, albeit somewhat more expensive than an SMG. Historically, weapons like this have been used by infantrymen of short stature, armour crews who had to be able to swing them into action from the cuppola, and soldiers who didn't want a bulky rifle such as paratroopers or men engaged in urban combat (in the jungles of Vietnam, soldiers were actually known to file down their gun barrels because they only got in the way). Another potential advantage of carbines is the strength of the short, stout barrel, which is suitable for rifle grenades.
While neither SMGs or carbines have been as widely adopted as assault rifles among the world's armies, this may change in the post Cold War era as armies gear up for an age of asymmetrical "brush fire" conflicts rather than full-scale warfare. The great range of an assault rifle is arguably an unnecessary and expensive extravagance for the majority of situations in which a soldier might find himself, and there is talk of drawing up a NATO standard for a PDW, or Personal Defense Weapon, which would fit the parameters of an SMG or carbine and which would be issued to the roughly two thirds of a modern army that has no need for an assault rifle's bulk, expense or range, such as tank crews, truck drivers, paratroopers, and Spec Ops commandos.
Assault Rifles
The
assault rifle is a handheld long gun which can be either
semi-automatic or fully automatic, and which is designed for
medium-range firepower. Its long, rifled barrel and solid
stock give it superior accuracy when compared to the SMG, the
carbine, or the handgun; for example, the C7 (the Canadian
designation for the M-16) has a specified effective range of 400-500
metres, although such ranges are probably academic under realistic
combat conditions (and it should be noted that on the firing range,
their useful range is said to be more like 200 metres).
The principle advantage of an assault rifle over a carbine derives from the sheer length of its barrel, which can be easily twice as long as the barrel of a carbine. This increases range, accuracy and penetration, all of which are important for the infantryman who plans to shoot at enemy soldiers over open ground. Scopes are rare, but that isn't really a disadvantage; sights are extremely rugged and will maintain alignment even under brutal treatment, while the same might not be said about a scope. Assault rifles are accurate, lightweight and powerful, hence their adoption by virtually all of the world's infantrymen.
However, it can be argued that in the post-Cold War era, the armies of tomorrow may organize themselves less for full-scale combat over open ground than the complex environments of the future, which are likely to be heavily skewed toward urban warfare, anti-terrorist activity, and global policing. Such environments make the 400-500 metre range of an assault rifle a purely academic point, thus making its extra expense highly questionable.
Sniper Rifles
The
sniper rifle is obviously designed for extreme long-range
accuracy. It is usually a single-fire weapon and there are two
types of sniper rifle: standard rifles which are "accurized"
(eg. picked out during manufacture and testing for unusually high
accuracy and/or modified for accuracy) and specialized weapons which
have been designed from the ground up for use in the sniper role.
These weapons usually have ballistic characteristics similar to those
of assault rifles, and the most accurate models can hit man-sized
targets from as much as 800 metres away. It should come as no
surprise that sniper rifles are usually equipped with sophisticated
targeting devices such as telescopic sights, rangefinders,
light-amplification scopes, etc. Some sniper rifles are also capable
of fully automatic fire, based on the rationale that if a sniper is
detected, he may need to defend himself with more firepower than a
single-shot weapon can provide. However, snipers look rather
unfavourably upon these dual-purpose weapons. The operating mechanism
of an assault rifle is rather different than that of a purpose-built
sniper rifle, and automatic fire will tend to throw components out of
alignment. Therefore, a dual-purpose weapon sacrifices accuracy in
the name of firepower, and since snipers generally work in pairs
anyway, this trade-off is unnecessary because the other man will
always have a proper support weapon ready.
There are also "heavy sniper rifles", which fire an extremely heavy bullet at very long range. These weapons can kill a man at a range of well over a kilometre (the current world record is a confirmed kill at 2430 metres by a Canadian special forces sniper in Afghanistan, using a McMillan TAC-50 heavy sniper rifle firing American-made .50cal ammunition). Such weapons are often powerful enough to be used as "anti-materiel rifles" as well, and can effectively disable a vehicle.
Machine Guns
The true machine gun is designed for sustained, long-range firepower. Both the SMG and the assault rifle, while highly capable weapons, have significant limitations. They can both fire at a very high rate (usually well over 600 rounds per minute), but neither is actually intended for anything more than a short burst. Their magazine capacities are generally limited to 20 or 30 rounds, and they might even incorporate a special "three-shot burst" setting. A true machine gun, on the other hand, is a heavier weapon than either the sub-machine gun or the assault rifle, it is often belt-fed, and it is intended to fire hundreds or even thousands of rounds in short order. Early machine guns had huge, water-cooled barrels, and later machine guns had smaller air-cooled barrels. Heat was the predominant problem, since the barrel of a machine gun could become red-hot after sustained use. However, advances in materials science eventually permitted the development of light machine gun barrels which could withstand extremely long periods of sustained fire without a barrel change; in one particular test at Fort Benning, Georgia in 1967, an M60 fired a 164 foot long belt of ammunition in a long, single burst! Sparks shot from the barrel with each of the last few hundred rounds, but it delivered the rounds to the target area and it survived the brutal test without serious damage.
Machine
guns achieve their superior range through stability rather than
ballistics; their bullets might not travel any further than the
bullets from an assault rifle, but the guns themselves have a
markedly reduced tendency to be thrown off-axis by their own recoil.
This means that they can effectively cover a small area from a long
distance away, unlike their somewhat more random peers. Their sheer
mass reduces the effect of recoil, the grips are usually closer to
the recoil axis, and they are invariably stabilized by a bipod,
tripod or vehicle mount of some sort, rather than being carried
entirely by the soldier (unrealistic Schwarzenegger & Stallone
one-handed M-60 firing techniques notwithstanding). The concept of
"range" is different for a machine gun than it is for most
other weapons; while the effective range of most weapons is dictated
by their ability to hit targets in single-shot mode, machine guns are
not meant to be used as single-shot weapons. Their effective range is
dictated by their ability to evenly scatter bullets over a
well-defined "beaten zone", not their ability to hit
bulls-eyes.
Therefore, machine guns rely on fixed sights rather than scopes for aiming, and they're usually used as support weapons, to control large areas by overlapping their fields of fire rather than sniping at individual targets. In fact, it isn't even necessary to see the target at all. Soldiers trained in the use of this weapon can aim it by plotting presighted positions into the tripod dials which control the gun's rotation and elevation, so that they can saturate a target area with bullets even at night, with zero visibility. Infantry can report the location of enemy troops, and the machine gun can open fire on the target area in much the same manner as an artillery piece! Naturally, it is best to place a machine gun in a position of high elevation so that it can most effectively cover a large battlefield area.
Hiram Maxim was one of the pioneers of machine gun design, having been the first manufacturer of true automatic weapons (all previous repeating guns were based on the gatling gun principle). He claimed to have been inspired by an 1882 conversation with an American acquaintance who said: "Hang your chemistry and electricity. If you want to make a pile of money, invent something which will enable these Europeans to cut each others' throats with greater facility!" This story may be apocryphal but the statement was prophetic; tens of millions of Europeans died in the coming decades, and weapons manufacturers like Maxim, Browning and Lewis became obscenely wealthy in the process. But leaving aside the moral issues, Maxim's 1887 model had an effective range of 2000 metres, thus proving that range does not necessarily increase with technology. Although some of the big Browning machine guns would eventually be effective out to a staggering 3000 metres, such heavy weapons have been largely abandoned in the modern infantry, which uses smaller machine guns with ranges around 1000 metres. The reality is that 3000 metre ranges are completely unnecessary, since the probability of engagement at such ranges is so small that it can essentially be ignored.
The incredible power of the heavy machine gun obliterated the massed infantry charge from the battlefield once and for all, thus forever changing the nature of infantry tactics. In the battle of Omdurman on September 2, 1898 (one of many one-sided slaughters during the brutal European conquest of Africa in the late 19th century), more than 50,000 natives brandished rifles and made a massed fixed-bayonet charge at 23,000 British and Egyptian soldiers. The natives took horrible casualties: 15,000 dead and an equal number of wounded. This devastation was caused by just ten Maxim guns, which fired a combined total of 34,000 rounds of ammunition and kept British casualties to a total of just 5 officers and 85 men. It is ironic that later, in both the Boer War and World War I, the same British army would send infantry at enemy machine guns in massed fixed-bayonet charges over open ground with similarly disastrous results, having apparently failed to learn from the lessons of their own history. Modern infantry tactics have evolved into squad movement (pioneered by the Germans in WW1), in which small groups of men, each under the command of an NCO, advance toward enemy positions while taking advantage of the natural cover provided by uneven terrain and covering one another by directing suppression fire at enemy positions.
Machine guns have been classified into light and heavy machine gun classes in the past, but it was deemed that the great firepower and range of the WW1-era heavy machine guns was unnecessary. Therefore, modern armies use a hybrid weapon known as a GPMG, or General Purpose Machine Gun. The GPMG is a machine gun which is capable of long-range sustained fire when mounted on a tripod, but which is also light enough to be equipped with a bipod and carried by a squad as a light machine gun. The most popularly known example is the M-60, but it seems to have few fans among professional soldiers world-wide. One of the most widely used models is the Belgian FN MAG, which fires 7.62mm rounds at 600-1000 rpm with a muzzle velocity of 840 m/s.