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A flash suppressor, also known as a flash guard, flash eliminator, flash hider, or flash cone, is a device attached to the muzzle of a rifle that reduces its visible signature while firing by cooling or dispersing the burning gases that exit the muzzle, a phenomenon typical of carbine-length weapons. Its primary intent is to reduce the chances that the shooter will be blinded in low-light shooting conditions. Contrary to popular belief, it is only a minor secondary benefit if a flash suppressor reduces the intensity of the flash visible to the enemy.〔Army Field Manual FM 3-22〕 A flash suppressor is different from a muzzle brake, although they are typically mounted in the same position and sometimes confused with each other. While the former is intended to reduce visible flash, a muzzle brake is designed to reduce painful recoil inherent to large cartridges and typically has no effect on visible flash. ==Rationale== Pre-20th century rifle designs tended to have longer barrels than modern rifles. A beneficial side effect of the long barrel is that the propellant is completely burnt before the bullet leaves the barrel, usually resulting only in a puff of smoke from the muzzle. However, if the same weapon's barrel is "cut down" (shortened), as is common in cavalry and jungle-combat adapted versions, the bullet would often leave the barrel before the powder was completely consumed, resulting in a bright flash from the muzzle.〔 When barrel lengths were dramatically decreased with the introduction of various shorter-barreled rifles and carbines, the flash became a serious problem during night-time combat, as the flash would imperil the shooter's night vision and would also make the shooter's position more apparent. Originally limited to "special purpose" roles, it was now expected that all infantry weapons with shorter barrels would experience this problem, and thereby be of limited use in low-light situations. Flash suppressors became common on late-World War II and later assault rifle designs, and are almost universal on these weapons today. Some designs such as those found on the AKS-74U serve a dual-role as a gas expansion chamber helping the shortened weapon's gas system function properly. Military flash suppressors are designed to reduce the muzzle flash from the weapon to preserve the shooter's night vision, usually by diverting the incandescent gases to the sides, away from the line of sight of the shooter, and to secondarily reduce the flash visible to the enemy. Military forces engaging in night combat are still visible when firing, especially with night vision gear, and must move quickly after firing to avoid receiving return fire. Limiting the amount of powder to what the length of a barrel can burn is one possible solution, but differences between individual cartridges mean that some cartridges will always have too much powder to be completely consumed, and the reduced powder load produces a lower projectile velocity. Muzzle flash can be controlled by using cartridges with a faster-burning propellant, so that the propellant gases will already have begun to cool by the time they exit the barrel, reducing flash intensities. Faster-burning powders, however, produce less projectile velocity, which reduces the accuracy due to introducing a more parabolic bullet flight path in place of a "flat" trajectory while also reducing lethality of the weapon by reducing the energy delivered on target. Flash suppressors reduce, or in some cases eliminate, the flash by rapidly cooling the gases as they leave the end of the barrel. Although the overall amount of burning propellant is unchanged, the density and temperature are greatly reduced, as is the brightness of the flash.〔 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「Flash suppressor」の詳細全文を読む スポンサード リンク
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