by Max Barry

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by The Unitary Technocracy of Etoile Arcture. . 337 reads.

G500 Modular Weapon System

This page is a work in progress by its author and should not be considered final.

G500 Modular Weapon System


Assault rifle

Place of origin

Etoile Arcture

Service history

In service

2005 - present

Used by

Etoile Arcture Ground Forces
Madurastan Army
Zinairian Army
Dominion Standard Regular

Parilisan Revolutionary Army
Burtilanan Army
Cazatanian Army
Minnysotan Army
Salcanian Army
Meriadni Army
Armée de Terre
Astograthian Army

Production history


Sequoia Weaponworks




Sequoia Weaponworks

Unit cost


Number built

A fair few I guess


See Variants

Specifications (G500A3 ABR)


3.38 kg empty,
3.77 kg loaded


1028 mm w/ stock
extended, 775 mm
w/ stock folded

Barrel length

470 mm


  • 6.5×39 mm Grendel

  • 6.8×43 mm Remington SPC

  • Action

    gas operated, piston
    driven, short stroke

    Rate of fire

    650-700 rounds/min cyclic

    Muzzle velocity

    ? m/s

    Effective firing range

    100 m

    Maximum firing range

    150 m

    Feed system

    30-round box mag


    rear aperture and front
    post w/ tritium inserts


    The G500 Modular Weapon System (G500 MWS) is a family of air cooled, short stroke gas piston operated, selective fire automatic rifles that fire from the closed bolt position. The G500 can be chambered in either the 6.5x39mm Grendel (6.5/8/800) or 6.8x43mm Remington SPC (6.8 SPC Spec II) intermediate combat cartridges. The design allows easy calibre swapping at the user level by a simple change of barrel, bolt head and magazine. Manufacturing is to ISO 9001 quality management standards by Sequoia Weaponworks LLC of New Harrisburg, Etoile Arcture, using high strength chrome-moly alloy steels and robust and lightweight polyamide thermoplastic materials. The G500 MWS has been the standard infantry longarm of all branches of the Etoile Arcture Defence Forces since 2005, and has also been adopted by the Gendemerie Forces and civilian law enforcement agencies. It is available in two basic variants: G500A3 Assault/Battle Rifle (ABR) with 18½ inch barrel (top), and G501KA3 Assault/Battle Carbine (ABC) with 16½ inch barrel (bottom). Modular features common to the family include:

    • Chamber with fixed head space for easy calibre swapping

    • No tools quick-detachable barrel/trunnion system for easy replacement and cleaning

    • Manually adjustable gas regulator to compensate for adverse environmental and operating conditions

    • Fully ambidextrous controls, non-reciprocating charging handle and left/right swappable ejection port

    • Three prong open-end flash hider with 51-tooth ratchet suppressor mount (Blackout 51T Flash Hider supplied by Advanced Armament Corp.)

    • Flip-up backup iron sights (Model 38 Stonewall Folding Sight supplied by Argus Industrial Manufacturing Inc, Kingsport, Amastol)

    • Both the upper and lower receivers are ventilated and either four-quadrant MIL-STD-1913 Picatinny monolithic accessory rails, or Vltor KeyMod Universal Mounting System and MIL-STD-1913 Picatinny polylithic accessory rails moulded directly on to the fore-end

    • Rail-mounted optical sights (SU-230/PVS Articulated Telescope supplied by Elcan, standard day sight with dual 4× long-range and 1× wide field-of-view, or MARS (Multipurpose Aiming Reflex Sight) supplied by ITL Optronics with integrated laser aiming pointer and Meprolight Mepro MX3 (3x magnifier), mounted behind sight, or night vision compatible XPS3 Transverse Red Dot Holosight supplied by EOTtech)

    • Rail-mounted electro-optical sights (SWORD T&D (Thermal and Day) weapon sight supplied by Safran with CCD day TV and uncooled thermal imager (384×288 FPA, 8-12 µm IR band) and digital boresighting, or ASPIS sight supplied by Selex Galileo with CCD day TV and uncooled thermal imager (320×240 FPA, 8-12 µm IR band), and visible and near infrared aiming laser pointers)

    • "Broomhandle" vertical foregrip w/ extendable bipod legs (GPS-02 supplied by Grip Pod Systems)

    • Can use polymer 20-, 25- and 30-round magazines w/ quick-change floor plates (cloned versions of Magpul PMAG 30), 60-round quad-stack 'casket' mags, 100-round BETA C-MAG drum mags, and 150-round dual-drum mags (SAW-MAG 150 supplied by Armatac)


    The G502KA3 Close Quarters Battle Rifle (CQBR) is a further iteration on the G500 MWS platform that is broadly intended as a replacement for pistol calibre submachine guns in urban fighting and close protection situations. This is achieved by combination of a lightweight compact short barrel rifle format factor (10½ inch barrel) and a full-power combat cartridge in .300 AAC Blackout (.300 BLK), a specialist 7.62×35mm cartridge that is optimised for close quarters knock-down power at effective engagement ranges of c.200-300 metres. The G502KA3 has a high order of parts commonality with other weapons in the G500 series, can use all the same accessories, and be suppressed by a fast-detach aftermarket silencer such as the SilencerCo SWR Specwar 762 and Advanced Armament Corp. 7.62-SDN-6 to effectively reduce firing signature even when using supersonic ammunition.

    The G500 MWS can also lend itself as a host platform for attaching aftermarket accessories and ancillary weapons. It can be configured with a underbarrel grenade launcher, "Masterkey"-style shotgun, or less-lethal riot/crowd control weapon mounted via the 6 O'Clock rail underneath the fore-end. The manufacturer has authorised a growing list of mission essential equipment to be available to commanders for issue to their troops, including:

    • DefendTex Metal Storm 3GL

    • Lyran Arms LY67 Widowmaker

    • FN Herstal MK 13 Mod 0 EGLM (Enhanced Grenade Launcher Module)

    • FN Herstal M303

    • Heckler & Koch AG-C/EGLM, AG36 and M320A1

    • Colt EAGLE Grenade Launcher

    • RM Equipment M203PI

    • Lewis Machine & Tools M203-2003 Rail Mounted Grenade Launcher

    • C-More Systems M26 MASS (Modular Accessory Shotgun System)

    • Thales Green Light Optical Warner (GLOW)

    • LAIX Arms LA-136 Cyclops Laser Dazzler

    The G500 MWS also provides the basis for two semi-automatic sniper and sharpshooter rifles that fire Match grade ammunition from 20 inch barrels. These are respectively the G550A3 Designated Marksman Rifle (DMR) chambered in 6.5x39mm Grendel (top) and SG555A3 Sniper Rifle (SR) chambered in 7mm-08 Remington (bottom), which offer superior terminal ballistics with long range sub-M.O.A. accuracy and each capable of delivering supersonic performance to 1,000 metres. The G550A3 is a long-barrel combat accurized version of the G500 MWS featuring a Match free floating 416R pre-hardened chromium stainless steel bull barrel with a 1:8 (203 mm) rifle twist ratio. The handguard is attached only at the receiver end, providing a fully floating barrel and avoiding any change in zero when used with a bipod. The free floating polylithic MIL-STD-1913/KeyMod quad rail system of the G500KA3 is retained, with Noveske KeyMod rail covers and a Harris swivel model bipod typically attached to these. A solid polymer buttstock is also fitted with plastic spacers to adjust for length of pull and has a adjustable cheek piece for eye relief. Match ammunition is fed from a straight 20 round capacity polymer magazine. The SG555A3 is is essentially the G550A3 model up-scaled to handle the larger 7mm-80 chambering. To enhance hit probability the SG555A3 is provided with optics, night sights and ballistic aids, as well as fully customisable furniture and equipment. It has the following features and accessories:

    • Lengthened gas system with accurized free-floating long heavy barrel

    • Reinforced composite gun tube constructed from an inner chromium plated steel Match liner fluted for stiffness and accuracy, wrapped in an outer carbon fibre reinforced polymer (CFRP) sleeve to eliminate resonance and mirage

    • Integral ported muzzle break/jump compensator compatible with aftermarket .30 calibre sound suppressors (is issued with TITAN-QD Suppressor supplied by Advanced Armament Corp.)

    • Extended free-floating MIL-STD-1913 Picatinny/STANAG 2324 quad rail system protected with 12-slot ABS plastic rail guards

    • Flat-top rail with 20 MOA of forward elevation and fully compatible with 34 mm Barrett scope rings. Has sufficient room for a day sight and night sight mounted in-line (is issued with 2.5-10x-52mm Tactical Riflescope or 5-25x-56mm Long Range Tactical Riflescope w/ 0.5 MOA MIL-DOT reticle supplied by Emerson Optronics Ltd.; Barrett Optical Ranging System (BORS) that precisely calculates the yardage of each shot; and L3 Electro-Optical Systems Clip-On Night Vision Device-Long Range (CNVD-LR) with GEN3 image intensifier tube that sees out to 1,800 metres); SpecterDR1-4× Dual Role Optical Sight w/ Mini Red Dot Sight above the tube and Clip-On Night Vision Device-Thermal 2 (CVND-T2)

    • Feeding from 10- or 20-round polymer magazines (cloned versions of Magpul PMAG 10 and PMAG 20 7.62mm magazines)

    • Harris swivel bipod w/ rail adaptor

    • Fixed buttstock with height adjustable side-saddle cheek piece and buttpad adjustable for length-of-pull using plastic spacers

    • Ergonomic target-type pistol grip with adjustable palm shelf



    A G500 MWS comprises upper and lower receivers connected by tool steel cross-bolts and mated at the rear via a pivoting latch secured by a single takedown pin. The receivers are trapezoid in shape with a single piece moulded grip/trigger guard and magazine well on the lower part. Construction is all-composite using lightweight and temperature insensitive GF/PA-6 glass fibre/polyamide-6 thermoplastic (30% glass-fibre reinforced Polyamide-6). This is a ultra-high strength, melt-processable, isotropic, amorphous, rigid-rod, self-reinforcing, polyparaphenylene material of high ruggedness and durability that resists temperature, humidity, shock, drop, and water exposure.
    Both the upper and lower receivers are ventilated and either four-quadrant MIL-STD-1913 Picatinny monolithic accessory rails, or Vltor KeyMod Universal Mounting System and MIL-STD-1913 Picatinny polylithic accessory rails moulded directly as a Picatinny flat-top receiver (full length) and 6 O'clock (half length) and KeyMod rails in the 3 and 9 O'clock positions on the fore-end. The rails free float the barrel to enhance accuracy. The receiver rail can mount any aftermarket sights, and typically mounts a three dot combat type backup iron sight (BUIS) with either a rotary diopter or flip-up peep rear sight and a blade foresight, both being adjustable for windage and elevation. Tactical accessories including combat optics, variable power scopes, clip-on night vision or thermal devices, tactical lights and illuminators, underbarrel grenade launchers, "Masterkey"-style shotguns, less-lethal riot/crowd control weapons and green laser dazzlers. These can be mounted and remounted on the rails without affecting boresight/zero retention and weapon accuracy.


    GF/PA-6 thermoplastic is used in construction of the side-folding buttstock that folds to the right and secures by means of a spring-loaded locking mechanism. Two stocks are provided, both capable of accommodating the 5th to 95th percentile male and female warfighter and are rugged enough to withstand the rigors of individual movement techniques. A lightweight skeletonized folding stock is preferred on carbines, and a folding stock with four-stage collapsing butt preferred on full length rifles, that has a non-adjustable cheek piece to provide eye relief.


    The barrel is cold rotary hammer forged over a precision mandrel from an oversized barrel blank of AISI 4140 chrome-moly high tensile steel (MIL-S 6758 chromium-molybdenum alloy steel). The bolt carrier group and gas regulator are made from AISI 8620 alloy steel. The bore, chamber and barrel are cased hardened and chrome lined to resist corrosion and gas erosion to ensure a long service life. Recoil springs and the return spring are made of high-strength abrasion, oil and solvent resistant polyurethane. The barrel is threaded for a M16-type i.e. 'bird cage' five-port quick-detach (QD) flash hider machined from case-hardened AISI 8620 bar stock steel and secured by a barrel nut detent. The hider has no downward facing port to reduce firing signature by eliminating the kick-up and blowback of dirt and dust particles toward the operator, and can attach a QDSS sound suppressor/muzzle compensator by ratchet mount to fully eliminate accoustic, flash, and blast signatures.



    The barrel, bolt carrier group and firing pin are configured inline to reduce muzzle climb and consist of a no tools quick-detachable barrel/trunnion system secured by two lugs for rapid in-field replacement. A fixed head space allows easy swapping between the two primary calibre's. The ejector port can be swapped for left or right-handed operation, with cut outs on both sides of the upper receiver. It incorporates a spring-loaded dust cover and a brass deflector that throws spent cases forward and away from the shooter at a safe 1 O'clock angle to help conceal their location and prevent striking fellow soldiers. All exposed steel parts have a matt black MIL-DTL-16232G manganese phosphate corrosion resistant and rust-proof finish. Moving parts are coated in a maintenance-free molybdenum-disulphide dry-film lubricant for further rust and corrosion resistance and ensures operation under the most extreme climate and temperature conditions.
    The G500 employs a conventional gas piston operating system consisting of a gas cylinder above the barrel mounted on a free-floating trunnion system, with a gas piston driving a bolt carrier and a rotating bolt to lock the breech. To control recoil a tappet feeds gas from the barrel to the gas cylinder, which contains a piston that drives rewardly on the rotating bolt as it rides the bolt carrier on two machined bolt guide rods held inside the receiver. Breech locking is by a rotating bolt connected to a barrel extension using twin front lugs, the locking and unlocking being controlled by a S-shaped cam track on the bolt carrier. The barrel itself free-floats the receiver isolating all mechanical movement and undesirable barrel resonance that can affect accuracy. The guide rods and the gas piston are respectively telescoped by recoil springs and a return spring and are shrouded by a free-floating ventilated handguard to dissipate heat and allow gas to vent to the atmosphere. There is a three-port regulator on the gas cylinder which is turned by a gas key between three progressively larger apertures. The default first position cleans the piston and regulator to prevent fouling of the action (self cleaning), while the other two positions release more return gas to compensate for adverse environmental or operating conditions. The port can also be closed off for shooting with a suppressor, for single shot operation or firing bullet-trap grenades.


    The weapon is hammer fired from the closed bolt position, with an automatic sear safety device to prevent out-of-battery misfires by blocking the hammer and firing pin until the breech has been closed and locked. A spring-loaded firing pin also prevents accidental discharges if the weapon is jolted or dropped. Non-reciprocating cocking handles are mounted on both sides of the receiver for ambidextrous handling, allowing the gun to be cocked quickly without taking the dominant hand from the tigger, and does not cycle with the bolt being locked in the forward position during firing.

    Fire control

    The pistol handle and trigger guard are built in one trigger group and are controlled by a Match two-stage trigger mechanism. The first stage has a 2.94 kg (6½ lb) weight of pull with a long initial take-up, and the second stage a crisp and light 1.36 kg (3 lb) pull with a short surprise break to release the sear. The safety/selector switch is ambidextrous and has been closely modelled on that used on the Heckler & Koch G36 assault rifle. The trigger group is of the "drop in" replaceable type, the standard trigger group allowing to execute single shot (semi-automatic) and sustained (full automatic) fire as indicated by pictograms. Alternatively a single shot, burst fire (with a 2- or 3-round burst) and sustained fire trigger group can be installed. The selector moves between all modes in only 90° of travel with a tactile click between each position.


    The feed system is fully STANAG 4179-compliant able to utilise both original equipment manufacturer (OEM) and aftermarket magazines. These include AR15-pattern steel, aluminium and polymer magazines with a reduction in capacity from 30 to 25 rounds to accommodate the larger diameter 6.5 mm Grendel ammunition, and polymer magazines manufactured by Sequioa Weaponworks (licensed copies of the Magpul PMAG 30 GEN2 design using steel-reinforced Zytel) that take a full 30 rounds of ammunition and have quick change floor plates to enable easy tactical magazine changes. For high reliability without stoppages only aftermarket magazines modified with a special Sequioa Weaponworks polymer four-way self-leveling/anti-tilt follower and chrome silicon wire spring are authorised for use in the G500 series to ensure propper fit and function.
    The G500 can also provide sustained semi-automatic and automatic fire, and can be be converted to an automatic rifle configuration by replacing normal box magazines with either quad-stack 'Casket' magazines (60 round capacity reduced to 45-50 rounds), Beta C-MAG 'dual-snail' drum magazines (100 rounds capacity reduced to 80-85 rounds) or Armatac SAW-MAG 150 drum magazines (150 rounds reduced to 120-130 rounds). When chambered in cartridges including the 6.8 mm Remington SPC, Russian M43, M67 and M74 cartridges, or in Alfegan 6.65 mm AF, high reliability 30-round Heckler & Koch steel STANAG magazines are preferred as they can reliably feed foreign-origin ammunition regardless of quality. Cheaper Orlite and Thermold brand magazines can also be used, and are constructed from high-melt-temp black nylon that is crush and impact resistant, with a steel reinforcement mesh imbedded in the top 38 mm (1½-inch) of the magazine to strengthen the feed lips.


    Etoile Arcture

    • Etoile Arcture Ground Forces

    • Etoile Arcture Special Forces


    • Madurastan Army


    • Zinarian Army


    • Dominion Standard Regular Army

    • Dominion Standard Special Force


    • Parilisan Revolutionary Army

    Central prestonia

    • Royal Army


    • Burtilanan Army


    • Cazatanian Army


    • Minnysotan Army


    • Salcanian Army


    • Meriadni Army


    • Armée de Terre

    • Force Marine

    • Forces Spéciales


    • Astograthian Army

    Telegram for purchasing options. Please consider approving this dispatch to increase its visibility.


    • Cartridge:

      • 6.5x39mm Grendel (6.5/8/800) @ 123 gr ball

      • 6.8x43mm Remington SPC (6.8 SPC Spec II) @ 115 gr ball

      • 7mm-08 Remington

      • .300 AAC Blackout

    • Action: gas operated, piston driven, short stroke

    • Locking: rotating bolt locking w/ 2 lugs

    • Weight:

      • G500A3 Assault/Battle Rifle (ABR): 3.38 kg empty, 3.77 kg loaded

      • G501KA3 Assault/Battle Carbine (ABC): 3.19 kg empty, 3.6 kg loaded

      • G550A3 Designated Marksman Rifle (DMR): 4 kg empty, 4.53 kg loaded

    • Overall length:

      • G500A3 Assault/Battle Rifle (ABR): 1028 mm w/ stock extended, 775 mm w/ stock folded

      • G501KA3 Assault/Battle Carbine (ABC): 978 mm w/ stock extended, 724 mm w/ stock folded

      • G550A3 Designated Marksman Rifle (DMR): 1066 mm

    • Barrel length:

      • G500A3 Assault/Battle Rifle (ABR): 470 mm (18½ in)

      • G501KA3 Assault/Battle Carbine (ABC): 419 mm (16½ in)

      • G550A3 Designated Marksman Rifle (DMR): 508 mm (20 in)

    • Rifling:

      • 6.5 Grendel @ six lands and grooves, right hand twist; 1 turn in 203 mm (8 in)

      • 6.8 Remington SPC @ six lands and grooves, right hand twist; 1 turn in 254 mm (10 in)

    • Muzzle device: three port open-end flash hider w/ 51-tooth ratchet suppressor mount

    • Barrel material double lapped, chrome lined/ chrome-moly-vanadium MIL-B-11595-E

    • Magazine interface: STANAG 4179 compatible

    • Feed type: 20- or 30-round, detachable box magazine, double column or 60-round casket magazine, quad column, or 100-round drum magazine, helical

    • Upper and lower receiver: glass-fibre/polyamide-6 (GF/PA-6) thermoplastic, moulded grip/trigger guard and magazine well

    • Hand guard: free-floating MIL-STD-1913 Picatinny/STANAG 2324, 12 o' clock full length flat-top rail, 3, 6, and 9 o' clock half-length rails or Vltor Keymod rails

    • Buttstock: side folding skeletonized or collapsing w/ non-slip buttplate

    • Sights: aftermarket iron sights, day optics, etc

    • Sling attachment: push button QD sling swivels w/ rail mount

    • Finish: matt black manganese phosphate MIL-DTL-16232G

    • Muzzle velocity:

      • 6.5 Grendel @ 810 m/s

      • 6.8 Remington SPC @ 785 m/s

    • Chamber pressure:

      • 6.5 Grendel @ 296.5 MPa (43,000 psi)

      • 6.8 Remington SPC @ 310 MPa (45,000 psi)

    • Maximum effective range vs point target:

      • 6.5 Grendel @ 700 m

      • 6.8 Remington SPC @ 600 m

    • Maximum effective range vs area target:

      • 6.5 Grendel @ 1,00 m

      • 6.8 Remington SPC @ 800 m

    • Maximum sighting range:

      • 1,000 m w/ iron sights or diopter sights graduated from 300-1,000 m

      • 300 m w/ collimated reflex sight

      • 800 m w/ magnified combat sight

      • 300-1,200 m w/ tactical telescope

    • Accuracy: 1.5-2 MOA or 0.5 MOA

    • Cyclic: 650-700 rpm

    • Practical rate of fire: 45 rpm single shots, 100 rpm automatic

    • Safety/selector: lever, ambidextrous

    • Trigger pull: 29.35 N + 13.34 N

    • Modes of fire:

      • safe + semi-auto + full-auto

      • safe + semi-auto + 3-rd burst + full-auto