Sniper rifle

Requirements include high accuracy, reliability, and mobility, concealment, and optics, for anti-personnel, anti-materiel and surveillance uses by military snipers.

The Lovat Scouts was a British Army unit formed in 1899 that was renowned for the expert marksmanship and stalking skills of its personnel.

In Germany, these trained snipers were given rifles with telescopic sights, which illuminated at night in order to improve their accuracy.

[8] By the end of World War II, snipers were reported to provide "reasonable accuracy" over 600 m (656 yd) with anything over this range being unpredictable.

Military snipers and sharpshooters may also be required to carry their rifles and other equipment for long distances, making it important to minimize weight.

Military organizations often operate under strict budget constraints, which influences the type and quality of sniper rifles they purchase.

Sniper rifles built or modified for use in law enforcement are generally required to have the greatest possible accuracy, but do not need to have as long a range.

Perhaps the single most important characteristic that sets a sniper rifle apart from other military or police small arms is the mounting of a telescopic sight, which is relatively easy to distinguish from smaller optical aiming devices found on some modern assault rifles and submachine guns (such as reflector sights).

Most telescopic lenses employed in military or police roles also have special reticles to aid with judgment of distance, which is an important factor in accurate shot placement due to the bullet's trajectory.

For a given cartridge, a bolt-action rifle is cheaper to build and maintain, more reliable, and lighter, due to fewer moving parts in the mechanism.

In addition, the absence of uncontrolled automatic cartridge case ejection helps avoid revealing the shooter's position.

Consequently, police forces tend to follow military practices in choosing a sniper rifle cartridge instead of trying to break new ground with less-perfected (but possibly better) ammunition.

Unlike many battle and assault rifles, the bores are usually not chromed to avoid inaccuracy due to an uneven treatment.

The end of the barrel is usually crowned or machined to form a rebated area around the muzzle proper to avoid asymmetry or damage, and consequent inaccuracy.

Sniper stocks are typically designed to avoid making contact with the barrel of the weapon to minimize the effects of environmental inconstancies.

Modern sniper rifle stocks tend to be designed around a rigid chassis, offer user adjustability to allow shooters of various sizes and shapes to tailor the stock to their personal preferences, and modular attachment points to accommodate low-light and daylight aiming optics, laser designators, and other accessories without the need for custom-made mounting interface kits.

Non-static weapon mounts, such as bipods, monopods, and shooting sticks, are also regularly used to aid and improve stability and reduce operator fatigue.

[22] The M24 Sniper Weapon System adopted in 1988 has a stated maximum effective range of 800 meters and a maximum allowed average mean radius (AMR) of 1.9 inches at 300 yards from a machine rest, which corresponds to a 0.6 MOA (0.17 mrad) extreme spread for a 5-shot group when using 7.62×51mm M118 Special Ball cartridges.

[21][23][24] A 2008 United States military market survey for a Precision Sniper Rifle (PSR) called for 1 MOA (0.3 mrad) extreme vertical spread for all shots in a 5-round group fired at targets at 300, 600, 900, 1,200 and 1,500 meters.

[25][26] In 2009, a United States Special Operations Command market survey called for a 1 MOA (0.28 mrad) extreme vertical spread for all shots in a 10-round group fired at targets at 300, 600, 900, 1,200, and 1,500 meters.

[29][30] In 2008, the US military adopted the M110 Semi-Automatic Sniper System, which has a maximum allowed extreme spread of 1.8 MOA (0.5 mrad) for a 5-shot group on 300 feet, using M118LR ammunition or equivalent.

[21][23][31] In 2010, the maximum bullet dispersion requirement for the M24 .300 Winchester Magnum corresponded[21][23] to 1.4 MOA (0.39 mrad) extreme spread for 5 shot group on 100 meters.

[32] In 2011, the US military adapted the .300 Winchester Magnum M2010 Enhanced Sniper Rifle, which had to meet an accuracy requirement to fire ≤ 1 MOA/0.28 mrad (less than a 2-inch shot group at 200 yards) before being released for fielding.

This allows snipers to take fewer risks and spend less time finding concealment when facing enemies that are not equipped with similar weapons.

Maximum range claims made by military organizations and materiel manufacturers regarding sniper weapon systems are not based on consistent or strictly scientific criteria.

This implies that variables such as the minimal required hit probability, local atmospheric conditions, properties and velocity of the employed bullet (parts), properties of the target, and the desired terminal effect are major relevant factors that determine the maximum effective range of the employed system.