Sniper rifle

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A U.S. Army soldier peers through a scope mounted atop his M-21 rifle during operations in Iraq
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A U.S. Army soldier peers through a scope mounted atop his M-21 rifle during operations in Iraq
A sniper rifle is a type of rifle used for engaging in the act of sniping, most purely a rifle used for shooting with great accuracy over long distances.
Contents

Features

The key feature of modern sniper rifles is reliable placement of a bullet often at comparatively long distances, with a design that supports this goal. Common features include precision manufacture, a highly reliable gun action, a precise scope or optical system, and almost always some support device 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. The scope is dependent on the rifle and intended engagement distance. Some large caliber sniper rifles are sighted out to 1500 m with ultra high-magnification scopes, while rifles intended for urban combat and more limited range would use much less magnification. Many modern rifles incorporate bipods to steady the rifle for accurate shooting.

Certain design features help modern sniper rifles place the bullet within a minute of arc:

  • Rifles are built to tight tolerances. In particular, the headspace is as small as possible.
  • The barrel is precise. The production method is less important. Good barrels' rifling can 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 with temperature.
  • 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 forearm, "front furniture" or sling. This makes the first shot more repeatable since it helps isolate the barrel from outside mechanical and thermal effects.
  • The action is affixed carefully to the stock. Often a plastic "bedding" compound is used. It increases the rifles' 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.
  • The end of the barrel may be counter-sunk a few millimeters to protect the critical exit-end of the rifling.
  • 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.
  • There is no correlation between barrel length and accuracy. Military sniper rifles tend to have longer barrels of around 300 mm to allow the cartridge propellant to fully burn and get the fastest bullet velocity for a given charge. Some police sniper rifles have shorter barrels to make them easier to handle. The shorter ranges at which police operate permit lower bullet velocities.

Types

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

  • A regular rifle or assault 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. The professional term 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 such as .50 caliber (12.7 mm) sniper rifles like the U.S. M107 or silenced ones, as in Russia's VSS Vintorez, are good examples of what can be accomplished in a dedicated sniper rifle, especially one devoted to a niche of the sniping field. 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 machineguns and even pistols can be used to snipe, but these clearly are not sniper rifles.

The main categories of use and resulting types include:

  • Military sniper rifles feature a focus on high durablity, use of highly available ammunition types (such as NATO 5.56 or 7.62 mm)
    • Close support sniper-rifles extend the range of infantry, a classic example being the SVD Dragunov.
    • Designated marksman rifle configuration such as M16A4 equipped with scope and bipod.
    • 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 more often bolt-action and usually have bipods (whereas ones used for close-support often do not) and very high power scopes.
    • Large-caliber sniper rifles use larger ammunition, especially 50-caliber (12.7 mm) rounds. There's 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. Prime example is the US XM107
      • 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.
  • 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.

History of sniper rifles

See sniping for the history of the field of sniping. Sniper rifle design developed alongside the people that use them.

Future of sniper rifles

Today sniping has diversified immensely and with it the rifles. Weapons technology advancements and new mission requirements are continually changing the rifles. The constants are a focus on accuracy and a scope for superior long-range target hit success, as compared to a sniper rifle's contemporaries.

Abridged list of sniper rifles and their calibres

For a Full listing see: List of sniper rifles

Small caliber 'Designated Marksman Rifles'

Semi-automatic sniper rifles

Bolt-action sniper rifles

Large caliber sniper rifles

See also

External links

zh:狙击步枪 ja:狙撃銃

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