Sniper rifle

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Image:Sniper rifle.jpgA sniper rifle is a vague class of rifle used for sniping or a similar use which requires a precision small arm (anti-materiel work, explosive ordnance destruction, and other related operations). It can be roughly defined as any rifle (primarily, though other weapons may be used depending on the situation) suitably accurate for the selective long-range and short-range destruction of specific small targets, often from a concealed position. The targets of sniper rifles can vary wildly, but are primarily human. Other targets may include attack dogs, searchlights, aircraft engines, ammunition or fuel stockpiles, explosives, or any other target of high tactical or strategic value capable of being destroyed or disabled by the weapon at hand. The organizations who purchase sniper rifles are usually military or law enforcement agencies. However, there is very little distinction between rifles used for sniping, and rifles used for any other activity that requires some degree of durability and accuracy. As such, most civilian bolt action rifles of reasonable quality (including obsolete antiques) could be suitable for sniping with little or no modification, depending on the skills of the sniper. This article will focus on rifles that are either well-suited for sniping because of their durability and quality of manufacture, or are specifically designed for the task.

1 Features
2 Types
3 History of sniper rifles
4 See also
5 External links

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Features

The key feature of modern sniper rifles is precise placement of a bullet, often at comparatively long distances. Any purpose built design must support this goal. Common features include precision manufacture, a highly reliable gun action (bolt or semi-automatic, roughly dependent on the preferance of the individual or agency), an accurate telescopic sight or other optical system, and almost always some support device (such as a bipod) for the shooter to fire from multiple positions. The need for high reliability and simplicity has resulted in many modern rifles continuing to be bolt action, though many are semi-automatic. Many snipers prefer the bolt action over the semi-automatic as the secondary click of a semi can give away their position, and a semi-automatic action adds recoil not found in bolt-actions. The scope's accuracy is dependent on the rifle and intended engagement distance. Some large caliber sniper rifles are sighted in to 1500 m (1640 yards) with ultra high-magnification scopes, while rifles intended for urban combat and more limited range would use much less magnification.

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Specific design features help modern sniper rifles place the bullet within a minute of arc, and are commonly included in most purpose built sniper rifles. Non-specific rifles might also have some of these attributes, allowing them to be used for this purpose. The features include:

A rifle built to tight tolerances. In particular, the headspace should be as small as possible.
The barrel is precisely manufactured. The production method is less important. A good barrel's rifling should be able to be cut with a lathe or swaged with a button. Some barrels have metallurgical treatments to reduce their internal strains, and thus the amount they bend or twist when temperature is increased.
A "free-floating barrel" is often used. The barrel is attached to the rifle at a single point, screwed into the action, not touching the stock or "furniture". The logic behind this is that a barrel expands very slightly while a bullet is passing through it, and if it came in contact with the stock, the barrel and consequently the bullet would be deflected slightly from the point of aim.
The action is affixed carefully to the stock. Often a glass, fiberglass, or plastic "bedding" compound is used. It increases the rifle's repeatability by reducing tolerances between the stock and action. Some engineers claim it raises the mechanical resonant frequency of the rifle, reducing the wavelength of resonances, and thus the total error from them.
Most sniper rifles have heavy barrels to increase the resonant frequency (again) and slow the rate of heating, which reduces thermal distortion of the barrel as more rounds are shot. This also increases the weight of the rifle, thus reducing the felt recoil.
The end of the barrel may be counter-sunk a few millimeters to protect the critical exit-end of the rifling from damage.
The trigger sears may be polished so the trigger releases crisply. This reduces the shooter's tendency to jerk the trigger, and move the point of aim. A good trigger lets off or 'breaks' cleanly without any 'creep.' It is said to feel like snapping a glass rod.
A low-mass (often titanium) hammer and pin reduce the time between the trigger pull and the primer ignition. This reduces the distance that a human being's irreducible quiver can move the point of aim.
Military sniper rifles tend to have longer barrels of around 23.5 inches (600 mm) to allow the cartridge propellant to fully burn and get the fastest bullet velocity for a given charge. This also reduces muzzle-flash, helping to keep the sniper concealed. Some police sniper rifles have shorter barrels to make them easier to handle. The shorter ranges at which police operate permit lower bullet velocities. The effect of barrel length on accuracy is negligible.

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Types

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The main types of rifle designs used as sniper rifles are:

A rifle fitted with a scope, bipod and sometimes other enhancements is a large and very common class of sniper rifles. Most modern assault rifles have a sniper variant as did many of their predecessors. A professional term for such weapons is "designated marksman" configuration.
A dedicated sniper rifle designed specifically for the field or some subset of it. This includes what is most often thought of as a modern sniper rifle, epitomized in weapons such as the Accuracy International AWP. Low rate of fire, high unit cost, integrated bipods, and scope mounting systems such as the Picatinny Rail, are often found in this class. Large caliber sniper rifles (technically 'anti-materiel rifles') like the .50 caliber (12.7 mm) U.S. M107 or silenced ones, as in Russia's VSS Vintorez, are good examples of what dedicated sniper rifles can accomplish, especially one devoted to a specialized niche. Rifles used for competition shooting would also often fall into this category.
Hunting rifles are often used as sniper rifles. Some of the first sniper rifles and many modern ones are derived from or are direct copies of hunting rifles. The deep ties between the two fields result in weapons that fulfill similar needs.
Other weapons and derivations exist that function as sniper weapons, although the use of the term 'rifle' may be debatable. Submachine guns, carbines, crew-served machine guns and even pistols can be used to snipe and outfitted with scopes, but these clearly are not sniper rifles.

The main categories of use and resulting types include:

Military sniper rifles feature a focus on high durability, use of highly available ammunition types (such as NATO 5.56 or, most commonly, 7.62 mm)
- Close support sniper-rifles extend the range of infantry, a role known as designated marksman in the US Army. A classic example is the SVD Dragunov or accurized M16A4s, equipped with scope and bipod (Such as the USMC SAM-R or US Army SDM-R).
- Standard sniping, with a sniper and spotter team, often use a rifle with higher range and reliability with a low rate of fire. They are usually bolt-action and usually have bipods (whereas ones used for close-support often do not) and high power scopes.
- Large-caliber sniper rifles use larger ammunition, especially 50-caliber (12.7 mm) rounds. There is a large similarity in use but two divergent focuses exist.
  - Use against enemy combatants. Used the same way as standard sniper rifles but with higher target effect or at extreme ranges (this use is somewhat limited by continuing debates over whether or not such action falls under the Hague Convention's specific prohibition of the usage of weapons "specifically calculated" to cause undue suffering).
  - Use against materiel targets, such as for ordinance disposal or against thin-skinned targets like parked aircraft or gas tanks. This field of use is also a part of the field of Anti-materiel rifles and light infantry anti-vehicle weapons.
  - Due to the similarity in function many large-caliber weapons in this category can be used in both roles.
Police Sniper Rifles often feature less rugged designs and don't have to adhere to military standards of durability and functionality, and are not restricted to certain ammunitions.
- Police sniper rifles more often feature compact or have a shorter barrel than their military counterparts due to the lack of need for high velocity long-range ammunition in the engagements.
- Police sniper rifles are often of relatively basic caliber, and usually are not large caliber. However, some police departments at least in the United States, are known to have large caliber rifles such as the Barrett M82.
Civilian rifles of high accuracy tend to fall into two categories, general and competition. In addition to user requirements they are often heavily influenced by regulations in regard to their design placed by governmental bodies. Competition rifles must abide by the standards of a given sporting regulatory body as well. Common non-competition weapons include ones used for hunting or general target practice. There is generally a higher focus on ease of use, customization, as well the inclusion of things like ornamentation of the weapon.

Many other ways of organizing sniper rifles into categories exist. The first highlights the difference in intent of design and the resulting characteristics. The second highlights intent of use and resulting characteristics.

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History of sniper rifles

The history of sniper rifles is irrevocably linked to the history of sniping. The development of purpose built weapons, however, is largely a 20th century phenomenon. For more info see: Template:Main.

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