NationStates

AR5R2 family of weapons. From top to bottom:
AR5R2 .45 CQC with folding stock, ICO-S, foregrip
AR5R2 5.56 Carbine with telescoping stock, ICO-S, taclight
AR5R2 5.56 Rifle with fixed stock, ICO-M, 40mm UGL
AR5R2 7.7 Rifle with marksman stock, ICO-L, bipod
Complete parts list
Complete magazines list

Designer: Arsenal Deimos
Designed: 2011
Manufacturer : IFAM
Unit cost: 1200- NSD
Produced: 2011-
Common Variants: AR5R2 5.56/7.7 CQC, Carbine, Rifle, AR5R2 .45

(statistics are for AR5R2 rifle.)

Weight: 3.65 kg
Length: 1000mm
Barrel length: 523 mm (20.59 in)
Cartridge: 5.56x45mm/7.7x54mm/.45 Arsenal Standard Anemonian
Action: Gas-operated (short-stroke gas piston), rotating bolt
Rate of Fire: 950/750/550 rpm
Muzzle velocity: 962 m/s (3,156 ft/s) (5.56)/875 m/s (2,781 ft/s) (7.7)
Effective range: 580 m (1,903 ft)
Feed system: 20 (7.7) or 30 (5.56/.45) round detachable box magazine.
Sights: Rear receiver fixed diopter sight (with flip-convertible small and large diameter sights) and front hooded post.

Background and History
The AR5R2 is, in many ways, a remarkable weapon. Developed from a service rifle long considered to be obsolete, it was created in response to various orders from nations such as the Confederate States of Arkinesia to the Federal Empire of Asakura, but the sheer ambition of its design and the ingenuity of those involved meant that, ultimately, the firearm produced would far outstrip the expectations of those who had initially ordered it.

Designed by the team responsible for the production of the initial AR5R1 from the ruins of the AR5, the -R2 standard rifle is a natural development of the AR5R1, with an additional and very notable focus on the modularity of the weapons system; its flexibility on the field of battle, and its ability to cater to the requirements of a large market niche. Ultimately, this means that it is, despite its misleadingly simple ergonomics and design base, a highly effective and modern weapon whose design gives its users the ability to make full use of a wide range of rounds via a series of ingenious design features.

Entering initial pre-production testing with the Crown Army of Anemos Major in Asakura during the early stages of 2011, field feedback suggests that the AR5R2 retains the battle-tested reliability of its predecessor while incorporating a number of significant new features that, in particular, have endeared it to special operations personnel.

Design

The AR5R2 is a development of the AR5R1 military service rifle, originally chambered in the 5.56x45mm round but adapted to be used as a multiple calibre modular service weapon capable of providing troops across the spectrum with a highly effective, multipurpose weapons system capable of filling any number of roles via inherent flexibility of design and a number of innovative features that make the AR5R2 among the most usable of small arms in existence today.

The AR5R2 manages to match and outperform the exceptional lightness of the AR5R1 by building upon the material base of its predecessor in a number of highly effective and innovative manners. The rifle's stock and handguard are constructed of glass-reinforced polymers, replacing previously metal components with single-piece 3:7 glass-to-polymer ratio parts (as utilised in the AR9 rifle). This balance of glass to polymer allows the AR5R2 to respond effectively to most battlefield needs, limiting weight significantly while ensuring that the weapons system is capable of withstanding harsh battlefield environments via high impact and applied force resistance. The material combination ensures that the AR5R2's external parts are able to endure long service periods without parts replacement, adding to its effectiveness as a battlefield weapon. The receiver itself is externally constructed of 3:7 fibreglass, while, internally, it is reinforced with chromoly (4140 steel), acting as heat absorbants and dissipators as well as recoil dampeners of sorts within the receiver to ensure that the receiver itself is not damaged by extended use.

The barrel is free floating, only in contact with the weapon at its attachment point on the receiver, and utilises explosively bonded bi-metallic button rifled barrels. This unique form of barrel construction, due to utilisation of explosive forming, a bi-metallic arrangement in place of a monolithic barrel construction, and button rifling, naturally costs more to produce than the cold hammer forged barrels popular with modern arms manufacturers. However, in consideration of the huge barrel life increases seen in comparative tests between non-clad and clad barrels, there is no doubt that significant long term savings are made despite the higher variable costs associated with this manufacturing method. Furthermore, the employment of high quality button rifling, together with the inherent long term resilience of these barrels, means that they are comparatively more accurate than cold hammer forged barrels, and capable of longer term accuracy retention.

This method of manufacture utilises high energy impact via a controlled explosive detonation to create an atomic-level, metallurgical bond between metals, allowing for the creation of a very strong bond and the creation of a true bi-metallic barrel in place of a monolithic steel barrel. This 'clads' metals together, rather than coating (as is the case with the chromium linings employed in most small arms barrels today). This increases barrel service life, as clad metals are less prone to wearing than coatings. These clad layers, marginally thicker than chrome coatings, prevent erosion and insulate the barrel. The AR5R2's barrel utilises a combination of tantalum, a metal with inherent wear and corrosion-resistance qualities that make it ideal for use in such environments, and 4150 steel (with chromium and molybdenum as primary alloying elements). Button rifling is employed to maximise the potential accuracy of the rifle system, with frequent equipment replacement and production lines employed to ensure that production quality is maintained alongside high production rates. The barrel's rifling consists of 6 right hand grooves and a 1 in 178mm twist rate (5.56mm barrel), 4 right hand grooves and a 1 in 325mm twist rate (7.7mm barrel), or polygonal rifling with a 1 in 400mm twist rate (.45 barrel).

Deconstruction of the weapon has been largely simplified and streamlined to ensure that parts, including calibre, conversion can be performed with relative ease. Removing the pins attaching the handguard to the main receiver block allow it to be slid down over the barrel, exposing part of the forward receiver and the barrel itself. Unscrewing the barrel assembly and removing it allows for the quick replacement of the barrel to fit different roles and, of course, calibres in a quick and simple process. In order to change the weapon's calibre, the upper receiver is tilted forwards, allowing for the receiver internals (which have been installed as part of a rapidly removable block) to be detached, pulled out and replaced with another. The trigger guard is then untightened via the screw attaching it to the pistol grip, which then swings down. The push pins on the magwell are removed, allowing for the replacement of the magwell with that of another calibre, which is then attached to the weapon. An adjustable gas regulator allows the rate of fire to be switched between 950, 750 and 550 rounds per minute to suit different roles and calibres. The utilisation of a short stroke gas piston system means that the rifle is far easier to disassemble and modify than a direct impingement weapon, as the receiver block can be removed and replaced without worries concerning gas flow.

The weapon itself utilises the rotating bolt and short-stroke gas piston employed by the AR5R1 rifle to retain the high reliability and controllability that made the original rifle the success it became. The short stroke gas piston consists of a piston assembly located in a tube above the barrel, into which the high pressure gases generated by the ignition of the cartridge enter through an intermediary gas channel (at 80 degrees to the bore axis). The piston is pushed back, thus cycling the action; a connecting assembly utilises the momentum of the moving piston to cycle the action of the rifle, with the propellant gases escaping through four gas vent holes, pushing back the bolt carrier, rotating and unlocking the bolt and thus cycling the weapon's action. The short stroke gas piston's advantages remain as they were in the AR5R1; the lack of direct interaction between the weapon's internals and gases, as was the case with the AR5's direct impingement, results in far greater levels of reliability during extended use due to the highly decreased level of internal fouling, while the lower mass of recoiling parts found in the short stroke gas piston system allows it to remain a highly controllable weapon. The ejection system is ambidextrous; with two ejection ports to either side of the receiver, a simple locking system allows for rapid conversion between left and right sided ejection, with a dual claw system where both claws are capable of acting as extractors and ejectors, reversing roles according to the position of the locking system. The charging handle is located behind the receiver in an AR-15 style arrangement to facilitate receiver removal and modification, and is non-reciprocating. This arrangement also ensures that the AR5R2 is fully and practically ambidextrous, and can be switched on the battlefield with minimal difficulty. The AR5R2 utilises a number of flash hiders; universally, however, their design revolves around their utilisation as muzzle brakes, venting both propellant gases and flash to either side of the bullet's trajectory to reduce recoil and the flash visible to those towards which the weapon is beind aimed. The band around the rear end of the flash hider is used to attach a number of muzzle accessories and additions, ranging from rifle grenades to suppressors to further increase the AR5R2's field versatility.

The feed device utilised in the AR5R2, across several calibres, has been updated to the standards of the polymer magazines employed in weapons such as the AR9R1 or AR3R3. The polymer construction of the magazine greatly increases its outward durability while decreasing its weight; the magazine is highly resistant to warping and other changes of shape under stress, thus decreasing the chance of those feed problems associated with damage in these areas occuring. Furthermore, the internal construction of the magazine is fully protecting, thus preventing damage to fragile components such as the feed lips. The internal construction of the magazine features a constant curve in the case of the 5.56mm magazine, removing bottlenecks where rounds could potentially jam and thus creates a relatively smoothly feeding magazine. The follower is constructed out of the same fibreglass utilised in the construction of the AR9 itself; shock resistant, and thus more reliable in the face of potential problems that could lead to feed irregularities, the polymer within the fibreglass construction of the follower means that it is also self-libricating, creating a highly reliable base for the magazine feed. The magazine also features indicator ports on the back, covered with transparent polymers to prevent the elements from entering the delicate internals of the magazine, that allow the operator to quickly determine the ammunition level of the weapon.

Sights on the AR5R2 are highly similar to those employed on the AR5R1, with the one significant change made being their removability to ensure their compatibility with the AR5R2's full length rail system. They are based around a circular enclosed rear diopter and a hudded front post with a three-pronged sighting profile. The ironsights are effective out to about 300 to 400 metres for point shooting; however, these wide diameter rear diopters are designed to allow for rapid target acquisition and elimination rather than accurate shooting. For higher levels of precision, the flip up rear dipters allow the shooter to access and utilise a smaller diameter diopter by pushing forward the general use sights forwards for accurate point fire out to and potentially beyond 650 metres. The sights are fully windage adjustable through a pair of rotating knobs on the rear sighting assembly and screws on the forward sights, together with photoluminescent inserts in both the rear diopter and front sights for night-time usage.

Ergonomically speaking, the AR5R2 is an oddity of sorts, choosing to remain with a standard layout construction in lieu of the bullpup arrangement favoured by many modern arms manufacturers. The ultimate objective was to make a weapon that was primarily modular, and thus simple in construction and composition; the standard layout was thus married with a highly minimalist design that nonetheless manages to remain highly effective. As such, areas of the weapon remain unchanged where modifications were not desirable; though the materials used have changed, the basic shape and texturing of the pistol grip remain constant, with relative weapons proportions being maintained to allow for increased familiarity with AR5R1 users. A number of changes have been made; the fire selector has been shifted and changed to allow for rapid receiver dismantlement, while further texturing was applied to components such as the magazine ejector to allow for easier access and use in combat. Recoil mitigation has been achieved in a number of stocks used with the weapons system via hydraulic buffers, reducing felt recoil significantly and allowing for the comfortable use of higher power cartridges.

Due to its modularity, the AR5R2's potential for modification for different roles is virtually limitless. At release, it is offered in three calibres, with a significant number of parts options that allow it to fill almost any conceivable role.

Developed in response to a 21st century requirement, the AR5R2 is very much a 21st century weapons system; featuring near-unrivalled modularity and flexibility in an innovative, effective package, it is a small arms system that assures battlefield dominance with its marriage of a tried and tested design and an innovative concept, capable of filling any and every role with exceptional performance.

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Enquiries concerning exports and comments should be made via telegram or to the Anemonian State Arms Export Authority.