The light machine gun 5.56×45 is designed to be employed by an individual gunner normally in an infantry squad. It is easier to handle by one person due to the weight and caliber of the ammunition and using the same ammunition as the others in the squad eases the logistics. The LMG is capable of delivering a large volume of effective fire which complements the effectiveness of all squad weapons across the spectrum of infantry operations. LMGs allow rifle squads to take light automatic weapons with them in the assault.

Modern 5.56mm Ammunition for Light Machine Guns and Rifles

The 5.56mm caliber is very useable for short range combat. Currently, there are many new 5.56mm ready ammunition types. Among these there are the so-called lead-free or low-emission characteristic (green ammo), and on the other hand new bullet constructions and higher projectile masses for ballistic performance improvement. Among the pioneers of producing lead-free ammunition, is Nammo. Since 2012, the Norwegian-Finnish company Nammo has supplied a revised lead-free 5.56mm cartridge with the label NM255 to the Norwegian Armed Forces. This has better performance compared to standard ball ammunition with minimized environmental impact. It has improved accuracy, terminal ballistics and barrel erosion, and better penetration compared to ordinary NATO ball. It contains no lead. This is a response to three years earlier lessons learned that the lead-free ammunition type NM229 could cause health problems when shooters were breathing copper and zinc vapor. The SS109 bullet of FN Herstal has a brass coat surrounding the steel and the underlying lead core. In 2010 the U.S. Army introduced the new M855A1 Enhanced Performance Round (EPR) with a 62-grain bullet. The double core construction with exposed bullet tip, mainly produced by ATK, also has a low emission and due to their component assembly it ensures higher efficiency. U.S. Special Forces also use the Mk262 cartridge with 77 grain bullet (5 gram). In 2010 the U.S. Marine Corps replaced the M855 initially with the MK 318 MOD 0 cartridge, caliber 5.56mm ball. Barrier penetrating, the 62 grain heavy “open-tip” -cartridge has a lead core and a thick copper base. The lead core is to make a breach into obstacles, which then the copper core penetrates behind. Meanwhile, the M855A1 is also used by the “Leathernecks.” RUAG Ammotec presented their HC + earlier in 2010. This lead free hard core cartridge with increased penetrating power is particularly suitable for light MGs. In May 2013 it qualified the lead-free cartridge 5.56×45 LF HC SX for the small Luxembourg Armed Forces. RUAG Ammotec announced this cartridge, exceeded the “multi caliber manual of proof and inspection” (MC-MOPI standard for test processes), which calls for a standard deviation of up to maximum 200 mm at a distance of 550 m, a standard deviation of 110 mm corresponds to 300 m. The lead-free cartridge 5.56×45 LF HC SX at this distance with all rounds had standard deviations of less than 50 mm.

The FN MINIMI 5.56mm Mk3, cover and feed mechanism assembly in open position. (Walter Håland)

The FN MINIMI 5.56mm Light Machine Gun

The MINIMI (short for French: Mini Mitrailleuse; “mini machine gun”) is a Belgian 5.56mm light machine gun developed by Fabrique Nationale (FN). The FN MINIMI is a gas actuated long-stroke piston system LMG firing from an open bolt. It is an air-cooled weapon capable of fully automatic fire only. It can be belt fed or fired from a magazine. The barrel is locked with a rotary bolt equipped with two massive locking lugs. It was first introduced in 1974. In the meantime it is in widespread use by the militaries of North America (designation M249), South America, Europe, South East Asia and Oceania. The weapon is currently manufactured at the FN facility in Herstal and at their U.S. subsidiary FN Manufacturing LLC. The weapon is primarily chambered for 5.56×45 NATO, though it is also available as a 7.62×51 NATO variant. The MINIMI is configured in several variants: the Standard model as a platoon or squad support weapon, the Para version for paratroopers and the Vehicle model as secondary armament for different vehicles. The welded receiver is made from stamped steel. Both the Standard and Para variants are equipped with a folding bipod mounted to the gas tube and stowed under the handguard. The bipod can be adjusted in height and each leg has three height settings. The bipod also offers a 15° range of rotation to either side. With the bipod fully extended, the bore axis is elevated to a height of 465 mm (18.3 in). The standard light machine gun version has a 465 mm (18.3 in) barrel Mk1 and a fixed composite stock with a folding shoulder strap. The shortened Para model has a 349 mm (13.7 in) barrel and a sliding metal stock. For 5.56 weapons, both these stocks are available with or without the hydraulic buffer that contributes to stabilizing the rate of fire and reducing recoil forces. The Mk3 configuration is only available with the hydraulic buffer. The weapon is fed from the left-hand side by disintegrating-link ammunition belts, from either an unsupported loose belt, enclosed in a polymer ammunition box with a 200-round capacity attached to the base of the receiver, or from reusable 100- or 200-round pouches, or from detachable 30-round STANAG magazines, used in other NATO 5.56 assault rifles such as the M16. Magazine feeding is used only as an auxiliary measure, when belted ammunition has been exhausted because this results in increased wear and tear on the rotary bolt’s locking lugs. This feature allows the FN MINIMI to be instantly changed from belt feed to magazine feed without any modification. When a belt is placed in the feed tray it covers the magazine port. The magazine port, when not in use, is closed with an L-shaped hinged flap equipped with a tooth, which engages a corresponding opening in the magazine and serves as a magazine release. The barrels used in the FN MINIMI have an increased heat capacity for sustained fire, feature a chrome-lined rifled bore (six right-hand grooves) and are manufactured with a 178 mm (1:7 in) twist rate used to stabilize the NATO SS109 projectile (since 1980s). The barrels have a quick-change capability; a lever is provided on the left side of the weapon that releases the barrel from its trunnion. A carrying handle is also fixed to the barrel that makes the barrel change process easy. A trained soldier can perform a barrel change and ready the weapon for aimed fire in 6-7 seconds. FN MINIMI has a cone-shaped slotted flash suppressor. Both the standard and Para models come with a rear sight, adjustable for windage and elevation. The sight has a peep aperture for ranges from 300 to 1,000 m in 100 m increments. The hooded front sight is installed in a post on the gas block. The gas valve is manually adjustable with two positions: normal and adverse. The adverse setting increases the cyclic rate of fire from 700–850 rounds per minute to 950–1,150 rounds per minute and is used only in extreme environmental conditions or when heavy fouling is present in the weapon’s gas tube.

The barrels have a quick-change capability; a lever is provided on the left side of the weapon that releases the barrel from its trunnion. The carrying handle fixed to the barrel is used in the barrel change process. A trained soldier can perform a barrel change and ready the weapon for aimed fire in 6-7 seconds. (Walter Håland)

The Trend in the 80s

As the other NATO nations, the Norwegian Defense also replaced at infantry squads the 11 kg heavy 7.62mm MG3, which is cumbersome to carry for an infantry soldier on foot patrols, compared to the 3 kg lighter FN Herstal MINIMI 5.56mm. The big MG3 is less suited to urban fighting. The 5.56mm ammunition is half as heavy as the 7.62mm. With the assault rifle HK416, in 5.56mm caliber, the infantry squad would only have one caliber, which makes it easier with supplying their ammunition to other members in the squad. The variant Norway has acquired is the MINIMI PARA TRIPLE RAIL with the sliding butt and rails for mounting of optical sight, light and laser pointer, or other selected accessories. The optical sight used on the MINIMI is the Aimpoint Comp 4x and 3x magnification. The delivered LMGs come with two different barrels. The 18.2 inch barrel is primary for use at maximum practical range. The additional 14.2 inch barrel is intended for shooting at shorter distances (Close Quarters Combat). The long barrel and the short barrel have different shaped flash suppressors.

The barrels have a quick-change capability; a lever is provided on the left side of the weapon that releases the barrel from its trunnion. The carrying handle fixed to the barrel is used in the barrel change process. A trained soldier can perform a barrel change and ready the weapon for aimed fire in 6-7 seconds. (Walter Håland)

FN MINIMI Mk3 (5.56mm and 7.62mm)

FN Herstal’s newest light machine gun line, the MINIMI Mk 3, is an update of the FN MINIMI. The FN MINIMI Mk3 is probably the most important new firearm of 2013 given its widespread use by the militaries. The company stated the new Mk3 was designed around the feedback received from actual combat troops using the weapon in the field. Essentially, all updates are focused on improved ergonomics and improved mobility. The most prominent updates are:

The old fixed stock has been replaced with a 5-position length of pull adjustable buttstock (to fit different sized soldiers with and without body armor). The stock has an integrated hydraulic buffer that stabilizes the rate of fire and reduces felt recoil. Additionally, the stock has an adjustable cheek riser and a shoulder rest. The user can have his eye correctly aligned with the iron sights, or optical sights, while keeping his cheek properly positioned on the buttstock.

A new handguard/bipod assembly that provides a comfortable handguard and three forward Mil-Std 1913 Picatinny accessory rails. The adjustable-height (3 positions) bipod, when folded back, integrates into the shape of the hand guard even with an accessory on the lower rail.

The top cover and feed tray has been upgraded for easier one-handed reloading. The cocking handle is more ergonomic and easier to operate with either the strong or weak hand.

The feed tray is improved with belt retaining pawls that hold the belt correctly in position during the loading procedure, which is most useful when the user is in the standing position.

According to FN Herstal, existing MINIMI machine guns can be upgraded to Mk 3 specs. FN offers complete or partial upgrades kit depending on customer’s needs. Upgrades can be performed in-house by the organizations. The MINIMI Mk3 will be available in two calibers (5.56 and 7.62). There will be four 5.56mm variants and three 7.62mm variants (down from the total of eight variants previously available). The 5.56mm variants are FN MINIMI 5.56 Mk3 Tactical LB (long barrel) and tactical SB (short barrel), – para and Tactical Standard.

The barrels have a quick-change capability; a lever is provided on the left side of the weapon that releases the barrel from its trunnion. The carrying handle fixed to the barrel is used in the barrel change process. A trained soldier can perform a barrel change and ready the weapon for aimed fire in 6-7 seconds. (Walter Håland)

M249 Light Machine Gun, Squad Automatic Weapon (SAW)

In the U.S. the light MG MINIMI in caliber 5.56×45 was adopted in 1982 and designated the M249 light machine gun (LMG), previously designated the M249 Squad Automatic Weapon (SAW), and formally written as Light Machine Gun, 5.56mm, M249 in use by U.S. Forces. Production for the U.S. military has been carried out entirely in the USA by a local subsidiary, FN Manufacturing LLC in South Carolina. U.S. Armed Forces, USSOCOM and the NSWC have been developing their own variants and upgrades of M249 for many years. The fruits of their labor are the Mk. 46 Mod 0/1 and Mk 48 Mod 0/1. As part of the U.S. military’s M249 Product Improvement Program (PIP), the M249 was updated with: a new synthetic stock and modified buffer assembly, a single-position gas regulator, a so-called birdcage type flash hider/compensator from the M16A2, a polymer barrel heat guard, and a folding carry handle. As a result, the weapon’s weight increased to 7.47 kg (16.5 lb.). Many of the PIP upgrades were later incorporated by FN for the MINIMI. The ergonomically-shaped polymer buttstock contains a hydraulic buffer that allows SAW gunners to maintain a high rate of fire with accuracy and effect.

Para

M249 Para

The M249 Para is optimized for airborne, armored infantry and close quarters combat (CQC) operations with a shorter barrel and sliding butt. It retains all of the features of the M249 SAW and can be field-converted back to the standard model configuration in just 30 seconds. Each M249 model includes one spare barrel.

Technical characteristics

Projectile weight: 3 g (77 grain)

Muzzle velocity: 1030 m/s (3377 fps)

Max. dispersion: S.D. < 200 mm at 550 m

Penetration: 12 mm RHA 300HB at 100 m

Service temperature: -54oC/+52oC

Safety temperature: -54oC/+71oC

Type classified by U.S. Army 1996 as M995. Nammo has been the sole supplier since then. In service in several countries. Combat proven and in production.

5.56×45 Armor Piercing 45 Incorporating Nammo’s knowledge on tungsten carbide technology as well as that on lead free projectile design, 5.56mm AP 45 provides a cost effective armor piercing round for use in assault rifles and machine guns. Military specified (STANAG 4172). The heavy projectile provides increased performance at long ranges.

Technical characteristics

Projectile weight: 4.5 g (70 grain)

Muzzle velocity: 915 m/s (3,000 fps)

Max. dispersion: S.D. < 200 mm at 550 m

Penetration: 7 mm RHA at 200 m

Service temperature: -54oC/+52o

Safety temperature: -54oC/+71oC

Status: In production

PARA Technical Data

Caliber 5.56mm x 45 NATO

Operating principle: Gas piston driven, hydraulic buffer

Bolt mechanism: Rotating bolt, open bolt principle

Feed mechanism: Belt feed from left side or magazine2

Modes of fire: Safe/Sustained fire

Length min/max: Long barrel 898 mm/1,028 mm, Short barrel 780 mm/914 mm

Height: 24.1 mm (9.5 inch)

Barrel length: Long barrel 466 mm (18.3 inch), Short barrel 347 mm (13.7 inch)

Sight: M/O3

Weight weapon with bipod: Short barrel (without ammo) ca 8.0 kg, With 100 rounds ammo pouch ca 9.1 kg

Trigger pull: 3.5 to 7 kg

Rate of fire: Automatic 14-15 rds./sec (approx. 850 rds./m)

Chamber pressure: ca 3,600 bar

Muzzle velocity-v0: Long barrel ca 925 m/s

Short barrel: ca 875 m/s

Muzzle energy-E0: Depending on ammunition/barrel

Barrel profile/twist: 6 grooves/right-hand twist 180 mm

Effective range: Ca. 400 m – 600 m

Max. range: Ca. 2,700 m

The version for the Norwegian Defense. Matte black or FDE color. 2 M416 magazines or 30-round STANAG magazines. 3 Aimpoint Comp M4 red dot sight and 3x magnification, Triple Rail, different accessories available.

Tactical Long Barrel

Tactical Short Barrel

Tactical Standard

N MINIMI MK3 Upgraded Components are highlighted in black. (Walter Håland)

Buttstock and buffer assembly. (Walter Håland)

Firing standard Ball and standard Tracer (full trajectory control out to normally 800 m)

5.56x45 Armor Piercing 3 significantly increases the war fighters’ lethality. Optimized projectile design with a tungsten carbide core for penetration of hard targets. Penetrates 12 mm RHA 300HB at 100 m and light body armor at normal combat distances.

On the cover rail of the MINIMI 5.56mm is the Aimpoint Comp M4 red dot sight with high battery compartment and 3x magnification, shown with plastic ammo box for a 200-round belt, handgrip, tactical light and Laser Designator (Forsvarets mediearkiv)

Presented in March 2012, it is the intention of Israel Weapon Industries (IWI) that the light machine gun (LMG) NG7 caliber 7.62 NATO will replace part of the Negev caliber 5.56×45 and part of the GPMG MAG 7.62×51 that are currently in use.

The design, as well as the action, the locking system and the operative system are clearly derived from those of the Negev 5.56 NATO, from which it inherits a good number of features.

The project, before going into production, faced an intensive period of field testing that the IDF nicknamed “ping-pong” that lasted about three years.  During this time several NG7 prototypes were issued to IDF combat units and returned to IWI with the related feedback.  Those feedbacks inevitably generated design modifications until a final version of the product, fully responding to specific Tsaha’l requirements, had been obtained.

The NG7 is equipped with an IWI ELOG system.  This electronically logs the real use of the weapon through a computer, allowing in turn the unit armorers to provide programmed maintenance according to real parameters and eventually to investigate any malfunction circumstances.

Operating System
The NG7 is a light machine gun (LMG) operated by a gas system called “gas impact.”  The firearm starts the shooting cycle with the open bolt to avoid cook-off after prolonged fire.  When the trigger is pulled the bolt, that is locked in a full rear position, is released and starts to go forward pushed by two compressed recoil springs.  During its travel a cartridge is taken from the belt, chambered and the bolt, thanks to its locking lugs, engages the corresponding lugs in the barrel extension and locks.  The bolt carrier, in this phase, keeps going forward, exposing the firing pin that strikes the cartridge primer.  Upon discharge, the bullet goes through the barrel, pushed by the rapidly expanding gas, until one third of the barrel length is reached, where the gas port is located.  A portion of the gas vents through the hole and runs through a regulating valve and the gas cylinder until it hits a short piston that is integral to two operating rods linked to the bolt carrier.  The gases then push back the piston and, through the two parallel operating rods, the bolt carrier located in the upper part of this subassembly that, operating a cam, makes the bolt head to rotate and unlock.  The cartridge is extracted and ejected along with the link of the feeding belt and, during the rearward movement, the bolt carrier operates the belt feeding mechanism making it advance and putting a fresh cartridge in position to be chambered until it reaches the maximum rear position.  If the trigger is kept pulled, and the fire selector is on the full auto position, the cycle is repeated until the weapon runs out of ammunition or the trigger is released.

Structure and Components
The NG7 structure is divided in four main groups: barrel, action, bolt/and bolt carrier, stock.

The NG7 can mount two different barrels, made by cold hammering process, of different lengths: one for the standard version 20-inch long (508 mm) barrel and one for the SF (Special Forces) version being 16.5 inches long (420 mm); both with 4 grooves right hand 1:12 inches (1 turn every 304.8 mm) rifling twist.  The chamber and bore are chrome lined to reduce barrel wear.  A 5 radial slot flashider is threaded on the muzzle and about one third of the total length there is the gas port block.  This component, mounted on the barrel by pressure and pinned, has three sub-components: gas regulator valve, gas cylinder and front sights.

The gas regulator valve, internally chrome lined to resist the high temperature of detonation gases, has only two positions instead of three, the assault rifle magazine feed option of the Negev in 5.56 is not present here: one for use in normal conditions and the other when the firearm is dirty, ensuring the correct operation of the gas system.  The front post-type sight, like the M16A1, is protected by two sturdy ears opened on the sides and adjustable both in elevation and windage to perform the mechanical zeroing.

A little before the cartridge chamber there is the carry handle that can be laterally folded and provided with a plastic grip for heat insulation.  It can also be used to remove the barrel when change is needed during a firing action.

Feed tray, with the feed lever protruding from the central slot. Note the wall of the feed tray shaped to allow a smooth belt feed.

The barrel ends with a barrel extension provided in the upper part with the lugs for fast locking it to the breech block.  Internally it shows the locking lugs to accommodate the bolt and completed with the feed ramp to facilitate correct cartridge chambering.

The NG7 body is made by ribbed and stamped steel sheets and assembled to machined steel and welded blocks.  The metal folding process is obtained using a particular industrial stamping method in order to obtain the metal box that forms the weapon’s receiver accurately respecting the project dimensions with minimal tolerances.

We can divide the weapon body in three sections: front, central and railed.  The front section is a stamped steel cradle where is attached by means of screws the plastic front handguard.  On the sides of the handguard, front portion, there are two short Picatinny rails to mount electronic devices such as target designators or any other electronic/optronic device useful for the mission.  At the front end of the action is welded the first steel block, used as a front support for the barrel, which also holds the gas cylinder and the locking base for the weapon bipod.  Welded on the left side there is the swivel ring to hook one end of the assault sling.  The NG7 bipod is folded toward the muzzle, allowing the shooter to aim the weapon not only to the left and to the right, but also to rotate it on its longitudinal axis and to be adapted to any configuration of the supporting surface.  In the central section is another machined steel block, welded to the action metal sheet.  The block shows at the front side the locking lugs to lock the barrel.  The action of locking and unlocking the barrel is operated by a side button, on the right upper part of the action, just before the receiver cover.

When a barrel is inserted in place during a barrel change, the top locking lugs, thanks to inclined plans, move sidewards to the corresponding metal projections until the insertion is completed.  At this point the barrel catch button is operated by a spring and returns to the initial position locking the barrel in place.

A safety mechanism on the left side of the barrel catch button does not allow that it can be depressed if the receiver cover is not opened.  The bottom of the steel block is milled to allow the bolt group to move; the rail section starts from the central block and reaches the rear end of the action, were the stock begins.  This section takes its name from the two rails that guide the bolt group during its cyclic movement.  They are welded to the internal walls of the action to ensure the maximum precision for a smooth operation while firing.

NG7 breech showing on the top of the barrel extension, the locking lugs to lock the barrel to the action.

On the right side of the rail section just behind the central block are two ejection ports: the upper one is for the links of the disintegrating ammunition belt, the lower one is for the spent cases.  Both are closed when carrying the weapon by two metallic lids to prevent dirt and debris from getting inside the machine gun’s mechanism.  Note that even being two different lids, they are articulated by a hinge.  When the lids are closed a little projection in the internal wall lower lid engages and locks to a notch in the bolt carrier.  When the bolt is armed and starts its rearward movement, the projection unlocks and, operated by springs, the two lids open and fold over the action.

The cocking knob is non-reciprocating and located on the right hand side.  Welded to the weapon is the related rail where the knob travels.  The cocking knob is provided with a ratchet safety mechanism to avoid accidental discharges of the gun if the cocking knob is not put in the full forward position after cocking the bolt.  The case ejector is internal, a pivoting type, located under the left bolt rail and operated by a suitable bolt carrier curve.

Different from its smaller “sister” in intermediate caliber, the NG7 does not have a magazine well for the assault rifle magazine nor the related lid to keep the dirt out.  This machine gun is belt fed only, from both a standard ammunition box or fabric and polymer drums with capacity of 100 or 125 7.62 NATO rounds, docked to the proper rail located in the lower part of the weapon body.  The absence of a magazine well opening allows the NG7 to take a great benefit in terms of action rigidity.