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 or 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.
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.
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 19 mm Ø, displaying a locking surface of 75 mm² (0.116 in²). 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.
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. 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.
The TRG system is almost unique in being a purpose-designed sniper rifle, rather than an accurised version of an existing, general-purpose rifle. The rifles can have a matte or manganese phosphatised finish.
The heart of the TRG system is a cold-hammer forged receiver and barrel. Both provide maximum strength for minimum weight as well as excellent resistance to wear. The "resistance free" bolt has three massive lugs and requires a 60-degree bolt rotation and a 98 mm (3.86 in) bolt throw for the short and 118 mm (4.65 in) bolt throw for the long bolt-action; these features should be appreciated by the shooter during multiple firings that require rapid projectile placement on the target. The bolt handle is the appropriate length and sports a large synthetic bulbous knob that provides a firm, positive grip. On top of the receiver a 17 mm (0.67 in) integral dovetail rail with shape connection drillings for one or more recoil lugs provides for fixing mounting components to accommodate different types of optical or electro-optical sights. Folding iron sights can be obtained for secondary or emergency use.
The receiver's large bedding surface is mated to an aluminium alloy-bedding block by three screws for maximum stability. This combination ensures an unusually high degree of stability.
The free-floating, heavy, chrome moly barrels (chrome moly barrels resist throat erosion better offering a longer accuracy life than stainless steel barrels) for the available cartridge chamberings all have a different length, groove cutting and rifling twist rate optimized for their respective chambering and intended ammunition. The .260 Remington, .308 Winchester, .300 Winchester Magnum and .338 Lapua Magnum chamberings are available with barrels of common length for sniper rifles and relatively short 510 mm (20.08 in) long barrels. On special order TRG rifles can also be supplied with stainless steel barrels.Two types of flash eliminator/muzzle brakes are available as an accessory with one being threaded to accommodate a sound-suppressor.
For the .260 Remington chambering a non-traditional 203 mm (1 in 8 inch) or 31.2 calibers right-hand twist rate optimized to stabilize longer, heavier very-low-drag bullets was selected over the standard 229 mm (1 in 9 inch) or 35.2 calibers twist rate. The TRG-22 can be ordered cambered for the .260 Remington cartridge as of May 2011. The introduction of the .260 Remington (6.5x51mm) chambering does not introduce major technical changes for the TRG system since the .260 Remington is essentially a necked down 6.5 mm (.264 in) variant of the .308 Winchester (7.62x51mm) cartridge, meaning these cartridges can be used in .308 Winchester chambered rifles only requiring different barrels.
For the .308 Winchester chambering the 280 mm (1 in 11 inch) or 36.7 calibers right-hand twist rate with four grooves was selected over the 305 mm (1 in 12 inch) or 40 calibers, traditionally found for the .308 Winchester, as a compromise when switching between supersonic and subsonic cartridges.
The .300 Winchester Magnum chambering also has a non-traditional 280 mm (1 in 11 inch) or 36.7 calibers right-hand twist rate.
For the .338 Lapua Magnum chambering a non-traditional 305 mm (1 in 12 inch) or 36.4 calibers right-hand twist rate was selected to optimize the rifle for firing 16.2 gram (250 grain) .338-calibre very-low-drag bullets. As of 2009 .338 Lapua Magnum barrels can also be supplied with a 254 mm (1 in 10 inch) or 30.3 calibers twist rate optimized to stabilize longer, heavier very-low-drag bullets like the Sierra HPBT MatchKing and Lapua Scenar .338-calibre 19.44 gram (300 grain) bullets. The traditional 254 mm (1 in 10 inch) has since become the standard twist rate for the .338 Lapua Magnum chambering.
The safety lever is located in front of the trigger inside of the trigger guard and can be operated without producing mechanical noise. The two-position safety locks the trigger mechanism, locks the bolt in closed position and blocks the firing pin. The safety is on when it is in its rearmost position. It is off when it is pushed to its most forward position. When the weapon is cocked the firing pin protrudes 1.6 mm (0.06 in) from the rear of the bolt-action, making it possible to feel if the weapon is ready to fire or not in poor visibility.
The two-stage trigger mechanism displays an adjustable trigger pull weight of 1 to 2.5 kg (2 to 5 lb) and can be adjusted for length, horizontal and vertical pitch. The advantage of these features is to prevent trigger movement in an inappropriate direction that would cause the rifle to move off target. Trigger travel is short with no noticeable over-travel. As a safety factor, a safety notch is incorporated into the trigger in order to prevent discharge resulting from a strong impact on the rifle. The smooth operating safety lever is located inside the trigger-guard. It locks the trigger mechanism in addition to locking the bolt in a closed position and to blocking the firing pin. The firing pin travel is 6.5 mm (0.26 in). The trigger mechanism can be removed without additional disassembling of the rifle.
The detachable box magazine is based upon centre feeding for maximum reliability as well as precise positioning of the cartridge into the chamber.
The TRG stock design is besides sniping requirements, designed to conform to both UIT and CISM regulations. Sako offers black, green, desert tan or dark earth coloured stock variants and the green, desert tan or dark earth stock variants are 0.2 kg (0.4 lb) heavier than the black variants. In 2011 Sako also began offering stocks in several styles of digital camouflage. The base of the ergonomic injection-moulded polyurethane forestock is made of aluminium and encompasses the bedding block with the bedding block serving as a point of attachment for a bipod. The polyurethane buttstock with its pistol grip and integrated aluminium skeleton to add strength, is designed for right- and left-handed shooters. The rear of the buttstock possesses a series of spacer and angle plates to regulate the length of pull and curvature adjustments that can be tailored for the individual shooter. The buttplate is adjustable for both height and pitch. Finally, the cheek-piece is adjustable for both height and pitch as well.
The stock features two steel sling swivel attachment sockets positioned at the right and left rear sides of the buttstock. Forward sling attachment is achieved by inserting and fixing a metal sling mount into a metal rail which runs under the forestock or fore end. This forward sling attachment point can be (re)positioned along the length of the rail for right- or left-handed use and is fixed with a screw. The factory carrying/shooting sling itself features quick mountable and detachable metal swivels. The swivels are mounted by pushing them into an attachment socket and detached by pushing integrated buttons in the swivels and pulling them out of the attachment sockets.
A folding skeleton type buttstock designed for right- and left-handed shooters is also available. The folding stock is 0.5 kg (1.1 lb) heavier than the non-folding green, desert tan or dark earth stock variants and is hinged behind the pistol grip; it folds to the left side and locks into position. When folded, the rifle becomes 250 mm (9.84 in) shorter. The steel parts of the folding stock are manganese phosphatised and the polyurethane parts are coloured olive drab or desert tan. The rear of the buttstock is adjustable for length of pull and height. The cheek-piece and rear support are also adjustable for height. These adjustment options allow shooters of various sizes and shapes to tailor the TRG folding stock to their personal preferences, which is an uncommon feature for folding stocks. The pistol grip body has a steel loop for a hook type military sling swivel. Sako TRG folding stock rifles are supplied with a Picatinny rail for mounting aiming optics.
The folding stock was later redesigned with the most conspicuous change being a bigger "foot" with an external lever/hinge support system monopod instead of the vertical moving small "spike" found on the earlier folding stock.
Sako accessories for the TRG system include auxiliary iron sights for emergency use, a muzzle brake/flash-hider, match sight mounting set, telescopic sight mounting sets, STANAG 2324 (Picatinny rail), accessory ITRS tri-rail for TRG forestock, accessory rail for TRG forestock (bottom), night sight adapter, silencer (sound suppressor), muzzle thread protector, various slings and swivels, cleaning kits, soft case, and a heavy-duty transit case. Several versions of TRG-specific bipods were produced that all lock into an attachment point in the aluminium bedding block at the end of the forestock. The latest bipod version is one of a few rifle bipods that lets the rifle swivel or "hang" just above its bore axis offering a more stable shooting position with large and heavy aiming optics mounted. It has a narrower leg angle due to complaints that the previous version interfered with some night vision systems mounted forward of the telescopic sight. Further versions of accessories are the ITRS tri-rail NV attachement point with an optional extended aluminium bedding block. This extended bedding block also can feature an optional STANAG 2324 Picatinny rail in the bottom of the block.
- TRG-21: .308 Winchester calibre version
- TRG-22: Upgraded and improved version of the TRG-21 with new stock design (maximum cartridge length 75 mm (2.95 in))
- TRG-41: .338 Lapua Magnum variant, there is also a version that fires the .300 Winchester Magnum round.
- TRG-42: Upgraded and improved version of TRG-41 with new stock design (maximum cartridge length 95 mm (3.74 in))
- Beretta TRG-42 Sniper: In October 2008 the Beretta TRG-42 Sniper, which is essentially a TRG-42 with a short barrel and folding stock with an integrated extended rail system, was presented by Sako importer Beretta USA at the Association of the United States Army (AUSA) Annual Meeting and Exposition as a possible platform for fulfilling United States Military .338 calibre Precision Sniper Rifle (PSR) solicitations.
- TRG M10: In October 2011 Sako unveiled the Sako TRG M10 Sniper Weapon System. The TRG M10 was designed as a user configurable multi caliber modular system and does not share its receiver and other technical features with the Sako TRG line. By changing bolts, magazines, fore ends and barrels in the field, the TRG M10 system can be switched between .308 Winchester, .300 Winchester Magnum and .338 Lapua Magnum chamberings and adapted to various requirements. At the introduction, the TRG M10 is marketed for "military and law enforcement only."
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