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Sako TRG-22/42 sniper rifles were developed by the Finnish firearm manufacturer SAKO of Riihimäki. The TRG-22 is designed to fire standard .308 Winchester〔Sako never mentions the military equivalent of the .308 Winchester - the 7.62 × 51 mm NATO cartridge (that has slightly different chamber specifications and a lower maximum chamber pressure compared to the .308 Winchester) - as a chambering option. For more information about the differences between the .308 Winchester and the 7.62 × 51 mm NATO cartridges read the (.308 Winchester Cartridge Guide: .308 Win vs. 7.62x51 - The Straight Scoop by AccurateShooter.com ) article.〕 ammunition, while the TRG-42 is designed to fire more powerful .300 Winchester Magnum and .338 Lapua Magnum ammunition and therefore has a larger action and barrel as standard. The rifles are available with olive drab green, desert tan/coyote brown, dark earth or black stocks, and are also available with a folding stock.〔(SAKO TRG sharpshooting system specification )〕 Normally muzzle brakes are fitted to reduce recoil, jump and flash. The Sako factory TRG muzzle brakes vent sideways and are detachable. Generally TRGs are outfitted with a Zeiss〔(Zeiss: Telescopic sights for handheld weapons )〕 or Schmidt & Bender PM II〔(Schmidt & Bender PM II )〕 telescopic sight with fixed power of magnification or with variable magnification. Variable telescopic sights can be used if the operator wants more flexibility to shoot at varying ranges, or when a wide field of view is required. ==History== In 1989 Sako Ltd. (Riihimäki, Finland) introduced the TRG-21 precision rifle as a sniper rifle model chambered for the .308 Winchester cartridge. A more hunting oriented variation of the TRG was later introduced as the TRG-S M995, which uses the same receiver (short action) and bolt (different bolt handle) as the TRG-21 with the exception that the receiver is open at the top rather than possessing a cartridge ejection port on the right side as found with the TRG-21. Subsequently, a second sniper rifle with a 20 mm longer scaled up magnum action emerged as the TRG-41 in order to take advantage of the .338 Lapua Magnum cartridge. Similarly, a hunting variant of this model, again using the same bolt (different bolt handle) and with the receiver open at the top was introduced as the TRG-S M995 Mag in magnum calibres up to .338 Lapua Magnum.〔(SAKO TRG-S specification )〕 Even though the TRG-21 obtained its origins from the successful Sako TR-6 target rifle, the 4.7 kg (10 lb 6 oz) TRG-21 was designed as a result of a thorough study of sniper requirements. With the introduction of the TRG bolt-action, Sako moved away from the modified two-lug Mauser bolt-actions, favoured during the past, to an action with a symmetrical three-lug bolt of diameter, displaying a locking surface of . The evolution of this design continues to the present and can be found in Sako's most recent hunting rifle offerings, the Sako 75 and the Sako 85. To make the TRG system more suitable for military use, Sako upgraded and improved the TRG-21/41 design in the late 1990s. Some TRG accessories like the muzzle brake and bipod (that lets the rifle swivel or "hang" near its bore axis offering a more stable shooting position with large and heavy aiming optics mounted) were also improved. This resulted in the TRG-22/42 rifle system. Around 2011 an American Sako vendor commissioned a special limited production run of TRG-22 rifles chambered for the .260 Remington cartridge and started offering these rifles as of May 2011.〔(EuroOptic Exclusive: .260 Remington TRG22s at www.accurateshooter.com )〕 In 2013 the TRG system was further upgraded and improved based on customer requirements. The upgrades consist of mounting improved recoil pads to reduce felt recoil, a newly constructed bolt release and a new fully adjustable two-stage trigger mechanism that features a new more ergonomic ambidextrous safety lever, and a trigger guard milled from aluminum for more positive magazine attachment. Further the bolt handle and its attachment to the bolt body were ruggedized. These general 2013 upgrades are backwards compatible with older TRG rifles. Exclusive for the .338 Lapua Magnum chambered TRG-42 model a new bolt featuring double plunger ejectors was introduced in 2013 to improve the ejection reliability of dimensionally large and heavy .338 Lapua Magnum rifle cases.〔(SAKO TRG 22/42 UPGRADE )〕 Sako never totally forgot the target rifle origins of the TRG system. The necessary accessories to attach sighting components such as match grade peep sights or target aperture sights and a mirage strap are all available. Equipped with these accessories the TRG can be used for non military or law enforcement tasks such as 300 m UIT standard rifle competition, CISM competition or other kinds of full bore target shooting. The rifle is commonly seen in long-range competition where it has done very well.〔(accurateshooter.com: Gun of the Week Collection, Week 69, TRG-22 for Competition - the Dutch Perspective by Jim de Kort )〕 Besides civilian target shooting the TRG system can and is sometimes used for hunting. The TRG system’s purposive design features, reliability in adverse conditions and consistent accuracy performance (a capable marksman can expect ≤ 0.5 MOA consistent accuracy with appropriate ammunition) have made it a popular, though expensive, sniper platform.〔A standard factory TRG-42 .338 Lapua Magnum user from Finland has reported on successfully hitting 45 x 90 cm (17. 7 x 35.4 in) reactive army targets from , and before a group of witnesses. The shooting area air density ρ was 1.228 kg/m³. This is slightly denser than International Standard Atmosphere sea level conditions (air density ρ = 1.225 kg/m³). Besides the rifle, ammunition (in this case handloads with GB488 16.2 g (250 gr) Scenar projectiles) and skill of the marksman, the employed sighting components, fire control software calculations and favourable atmospeheric conditions are also important to hit point targets at those ranges. See (Amazing Trajectory )〕 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「Sako TRG」の詳細全文を読む スポンサード リンク
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