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Bolt action is a type of firearm action in which the weapon's bolt is operated manually by the opening and closing of the breech (barrel) with a small handle, most commonly placed on the right-hand side of the weapon (for right-handed users). As the handle is operated, the bolt is unlocked, the breech is opened, the spent cartridge case is withdrawn and ejected, the firing pin is cocked (this occurs either on the opening or closing of the bolt, depending on design), and finally a new round/cartridge (if available) is placed into the breech and the bolt closed. Bolt-action firearms are most often rifles, but there are some bolt-action shotguns and a few handguns as well. Examples of this system date as far back as the early 19th century, notably in the Dreyse needle gun. From the late 19th century, all the way through both World Wars, the bolt-action rifle was the standard infantry firearm for most of the world's militaries. In military and law enforcement use, the bolt action has been mostly replaced by semi-automatic and selective-fire firearms, though the bolt action remains the dominant design in dedicated sniper rifles. Bolt-action firearms are still very popular for hunting and target shooting. Compared to most other manually operated firearm actions, it offers an excellent balance of strength (allowing powerful cartridge chamberings), ruggedness, reliability, and potential accuracy, all with light weight and much lower cost than self-loading firearms, and can also be disassembled and re-assembled much faster due to fewer moving parts. The major disadvantage is a slightly lower practical rate of fire than other manual repeating firearms, such as lever-action and pump-action firearms, and a far lower practical rate of fire than semi-automatic weapons, but this is not a very important factor in many types of hunting, target shooting, and other precision-based shooting uses. ==History== The first bolt-action rifle was produced in 1824 by Johann Nikolaus von Dreyse, following work on breechloading rifles that dated to the 18th century. Von Dreyse would perfect his ''Nadelgewehr'' (Needle Rifle) by 1836, and it was adopted by the Prussian Army in 1841. It became the first bolt-action weapon to see combat in 1864.〔Dupuy, Trevor N., Colonel, U.S. Army (rtd). ''Evolution of Weapons and Warfare'' (Indianapolis: Bobbs-Merrill, 1980), p.293.〕 The United States purchased 900 (Greene rifles ) (an under-hammer, percussion-capped, single-shot bolt action that utilized paper cartridges and an ogivial-bore rifling system) in 1857, but this weapon was ultimately considered too complicated for issue to soldiers and was supplanted by the Springfield rifle, a conventional muzzle loading rifle. During the American Civil War, the bolt-action Palmer carbine was patented in 1863, and by 1865, 1000 were purchased for use as cavalry weapons. The French Army adopted its first bolt-action rifle, the Chassepot rifle, in 1866 and followed with the metallic-cartridge bolt action Gras rifle in 1874 . European armies continued to develop bolt-action rifles through the latter half of the Nineteenth Century, first adopting tubular magazines as on the Kropatschek rifle and the Lebel rifle, a magazine system pioneered by the Winchester rifle of 1866. Ultimately the military turned to bolt-action rifles using a box magazine; the first of its kind was the M1885 Remington–Lee, but the first to be generally adopted was the British 1888 Lee–Metford. The Mauser Gewehr 98 was considered the epitome of this type of action, and its descendents became the standard against which all such rifles are measured. World War I marked the height of the bolt-action rifle's use, with all of the nations in that war fielding troops armed with various bolt-action designs. During the buildup prior to World War II, the military bolt-action rifle began to be superseded by the semi-automatic rifle and later assault rifles, though bolt-action rifles remained the primary weapon of most of the combatants for the duration of the war; and many American units, especially USMC, used bolt-action '03 Springfields until sufficient M1 Garands were available. The bolt action is still common today among sniper rifles, as the design has potential for superior accuracy, reliability, lesser weight, and the ability to control loading over the faster rate of fire that alternatives allow. There are however, many semi-automatic sniper rifle designs, especially in the designated marksman role. Today, bolt-action rifles are chiefly used as hunting rifles. These rifles can be used to hunt anything from vermin, to deer, to large game, especially big game caught on a safari, as they are adequate to deliver a single lethal shot from a safe distance. Bolt-action shotguns are considered a rarity among modern firearms, but were formerly a commonly used action for .410 entry-level shotguns, as well as for low-cost 12 gauge shotguns. The M26 Modular Accessory Shotgun System (MASS) is the most advanced and recent example of a bolt-action shotgun, albeit one designed to be attached to an M16 rifle or M4 carbine using an underbarrel mount (although with the standalone kit, the MASS can become a standalone weapon). Mossberg 12 gauge bolt-action shotguns were briefly popular in Australia after the 1997 firearms law changes, but the shotguns themselves were awkward to operate and only had a three-round magazine, thus offering no practical and real advantages over a conventional double-barrel shotgun. Some pistols utilize a bolt action, although this is uncommon, and such examples are typically specialized target handguns. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bolt action」の詳細全文を読む スポンサード リンク
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