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61-539: The Minimi fires from an open bolt . It is an air-cooled, gas operated long-stroke piston weapon that is capable of fully automatic fire only. It can be belt fed or fired from a magazine . The Minimi is configured in several variants: the Standard model as a platoon or squad support weapon, the shortened Para version for paratroopers and the Vehicle model as secondary armament for fighting vehicles. The Minimi uses

122-476: A chrome -lined rifled bore (six right-hand grooves) and are manufactured in two versions: with a 178 mm (1:7 in) twist rate used to stabilize the heavier Belgian 5.56×45mm SS109 projectile, or a 305 mm (1:12 in) twist for use with American M193 ammunition. The barrels have a quick-change capability; a lever is provided on the left side of the weapon that unlocks the barrel allowing the shooter to push it forward removing it from its trunnion. A carrying handle

183-434: A gas-actuated long-stroke piston system. The barrel is locked with a rotary bolt , equipped with two massive locking lugs, forced into battery by a helical camming guide in the bolt carrier. Upon firing, the piston is forced to the rear by expanding propellant gases bled through a port in the barrel near the muzzle end. The piston rod acts against the bolt carrier, which begins its rearward motion guided on two rails welded to

244-453: A 349 mm (13.7 in) barrel and a collapsible metal stock, while the vehicle-mounted model has a 465 mm (18.3 in) barrel but does not have a stock or iron sights . All models can alternatively be fitted with a fixed synthetic stock, the same used on the M249, which contains a hydraulic buffer that contributes to stabilizing the rate of fire and reducing recoil forces. The weapon

305-431: A closed-bolt firearm, this latency problem is generally less of a concern in full automatic fire and mostly applies to semi-automatic mode. The issue was most problematic in the use of forward-firing open-bolt machine guns and autocannons in ( tractor configuration single-engine) fighters during the piston engine era. Given the highly dynamic nature of aerial combat, the aforementioned intrinsic firing delay of open-bolt guns

366-412: A firing pin pressing on it with some force, but not enough to ignite the primer, which requires a sharp, focused impact. However, the weapon would be at risk of firing if dropped, much like the danger of loading spitzer bullets into a weapon with a tube magazine . A related issue is that the safety of an open-bolt weapon must be designed to lock the bolt in the rearward position. Often safeties only block

427-637: 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. A lightweight variant of the Para with a Picatinny top cover rail adapter is known as the Minimi Special Purpose Weapon (SPW). It had the magazine feed port removed to further reduce weight, and a railed MIL-STD-1913 handguard

488-427: A higher rate of fire is often desirable. In these situations, ammunition and recoil are less of a concern and the higher rate of fire will increase the likelihood of a round hitting the target, particularly when employed against fast-moving targets such as aircraft. Many movies and video games portray open-bolt weapons as needing to be cycled after reloading. This is not generally true, however, as open-bolt weapons send

549-423: A hinged sheet metal ejection port cover that doubles as a safety; when closed, it both covers the ejection port and blocks the bolt from closing. When ready to fire, the user simply flips the cover down, opening the ejection port and unblocking the bolt. An open-bolt weapon will typically have a higher rate of automatic fire than a comparable closed-bolt weapon as the bolt simply needs to return forwards in order for

610-424: A non-adjustable, self-regulating gas system and a hydraulic recoil buffer in the buttstock assembly. The Minimi 7.62 also has a different sight setup calibrated for the larger cartridge. The rear sight is adjustable from 300–1,000 m (980–3,280 ft), in 100 m (330 ft) increments. The sight can also be corrected for windage. The Minimi 7.62 TR is a variant equipped with a Picatinny rail handguard from

671-410: A rear sight, adjustable for windage and elevation, that provides a peep aperture for ranges from 300–1,000 m (980–3,280 ft), in 100 m (330 ft) increments. The sight line radius is 490 millimeters (19.3 in). The hooded front sight is installed in a post on the gas block and is also adjustable for elevation and windage. Early models of the Minimi had the rear sight mounted forward of

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732-473: A result of favourable reviews of the Mk 48 Mod 0 and increasing demand for a more powerful variant of the Minimi, FN Herstal introduced the Minimi 7.62. In November 2006, a FN Herstal press release said the Minimi 7.62 had recently been "launched onto the market" and was available "with a fixed or telescopic buttstock and a standard or triple rail handguard". Apart from the different caliber, the Minimi 7.62 incorporates

793-561: Is a 1982 standard by the Ministry of Defence of the United Kingdom. This Defence Standard specifies 7.62 mm small arms ammunition and its associated chargers and links for use by the Ministry of Defence to meet its commitment to NATO in the United Kingdom. The United States Army MIL-DTL-45403E (3) CONT. DIST. - Link, Cartridge, Metallic Belt, 7.62 Millimeter - M13 2021 specification covers the requirements and verification methods for

854-468: Is also fixed to the barrel and assists in the barrel change process. A trained soldier can perform a barrel change and ready the weapon for aimed fire in 6 to 7 seconds. Early models of the Minimi had a flash suppressor with side ports as seen on the FN FAL , FN CAL , and FN FNC rifles; new production guns have a shorter, cone -shaped slotted flash suppressor. Both the standard and Para models come with

915-479: Is because prior to the Hughes Amendment in 1986 , most semi-automatic open bolt Mac-10s, Mac-11s, and several other models were lawfully converted to full auto making these rare semi-automatic open bolts even more desirable as collector's items. However, there are many open-bolt firearms, that were designed from start to be semi-automatic firearms and are not classified as machine guns . The Fox Carbine

976-470: 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. This feature was developed by FN's Maurice V. Bourlet and allows the Minimi to be instantly changed from belt feed to magazine feed without any modification. The pawl-type feeding mechanism is modelled on the system used in the MAG general-purpose machine gun , which

1037-429: Is contained inside the receiver housing. Spent casings are removed through a port located at the bottom of the right side of the receiver, protected from debris with a spring-loaded dust cover. The Minimi is striker-fired and the bolt carrier functions as the striker mechanism. The Minimi has a push-button type manual safety installed in the trigger housing, above the pistol grip. In the "weapon safe" position, it disables

1098-457: Is fed from the left-hand side by disintegrating-link M27 ammunition belts (a miniaturized version of the 7.62mm M13 belt), 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 detachable STANAG magazines , used in other NATO 5.56 mm assault rifles such as the M16 and FNC . Magazine feeding

1159-534: Is of less importance. Thus, the improved heat dissipation of open-bolt designs is generally more desirable in automatic weapons. Submachine guns were for much of their life designed with open bolts such as the Thompson submachine gun , MP-40 and the Uzi , mainly for the simplicity and economical advantages, and their rates of fire and close-range nature mitigated the reduced accuracy of the design. SMGs used and built in

1220-415: Is one such example of an open-bolt firearm that was ruled to not be a machine gun. M13 link The M13 link, formally Link, Cartridge, Metallic Belt, 7.62mm, M13 , is the U.S. military designation for a metallic disintegrating link specifically designed for ammunition belt-fed firearms and 7.62×51mm NATO rounds . It was introduced in the mid-20th century. It is the primary link type for

1281-452: Is particularly undesirable. The inertia and latency inherent to the open bolt design negatively affects predictability and control and makes fitting open-bolt designs with synchronization gear to fire through the propeller blades difficult and often requiring extensive modification (but not impossible). Furthermore, with unlocked simple blowback action designs, calibers over 9×19mm Parabellum become increasingly less practical because of

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1342-687: Is technically very similar to the M1 link but designed for 12.7×99mm NATO / .50 BMG ammunition used in heavy machine guns like the M2 machine gun . The M1 and M9 links are pull-out designs. Rounds are extracted by pulling them rearward out of the link. The NATO Standardization Agreement STANAG 2329 Links for Disintegrating Belts for Use with NATO 7.62mm Cartridges described the M13 link in 1982. STANAG 2329 has been rendered inactive. The DEF STAN 13-33 - Standard NATO 7.62 Millimetre Rounds and Associated Chargers and Links

1403-403: Is used for fully automatic weapons and not for semi-automatic weapons (except some semi-automatic conversions of automatic designs). Firearms using advanced primer ignition blowback inherently fire from open bolt only. Compared to a closed-bolt design, open-bolt weapons generally have fewer moving parts. The firing pin is often part of the bolt, saving on manufacturing costs; the inertia of

1464-440: Is used only as an auxiliary measure, when belted ammunition has been exhausted. The ammunition belt is introduced into the feed tray, magazines are seated inside the magazine port at a 45° angle, located beneath the feed tray port. When a belt is placed in the feed tray it covers the magazine port. Likewise, a magazine inserted into the magazine well will prevent the simultaneous insertion of a belt. The magazine port, when not in use,

1525-419: The bolt and working parts are held to the rear of the receiver, with no round in the chamber. When the trigger is actuated, the bolt travels forward, feeds a cartridge from the magazine or belt into the chamber , and fires that cartridge in the same movement. Like any other self-loading design, the action is cycled by the energy released from the propellant, which sends the bolt back to the rear, compressing

1586-437: The receiver walls, while the bolt itself remains locked. This sequence provides a slight delay that ensures chamber pressure has dropped to a safe level by the time a cam in the bolt carrier rotates and unlocks the bolt, increasing extraction reliability as the empty cartridge casing has had the time to cool down and contract, exerting less friction against the chamber walls. The Minimi fires from an open bolt , which reduces

1647-535: The Belgian FN360° tripod or the American M122 mount using an M60 pintle. The vehicle-mounted Minimi is fitted with an electrically powered trigger that enables it to be fired remotely from within an armoured fighting vehicle. The standard light machine gun version has a 465 mm (18.3 in) barrel and a skeletonized aluminium stock with a folding wire shoulder strap. The shortened Para model has

1708-455: The Link, Cartridge, Metallic Belt, 7.62mm - M13 for use in 7.62mm machine guns. The M13 link is a push-through design. Rounds are extracted by pushing them forward out of the link. The left side of a single link has a semi-circular loop which holds the main body of the cartridge case below the shoulder, and an extension on the right that forms two similar loops which were designed to fit in between

1769-439: The M13 link should be between 8.5 and 18  lb f (37.8 and 80.1  N ) and the belt have a minimal tensile strength of 55  lb f (244.7  N ). A single M13 link weighs approximately 4.35  g (67.1  gr ). The links often have an extra anti-corrosion surface treatment, generally (oil impregnated) black phosphate , and can be collected and reassembled by hand with fresh ammunition, but in practice this

1830-587: The Mk 46 Mod 1 with an improved forward rail and lightweight titanium bipod has been adopted by the United States Navy . The Minimi prototype was originally designed in 7.62×51mm NATO , and later redesigned for the 5.56 mm cartridge. When the USSOCOM issued the requirements for the Mk 48 Mod 0 in the early 2000s, the original plans for the Minimi were retrieved and used to develop this new model. As

1891-675: The Mk3 features. The Minimi is being licence-built in Canada, Australia, Italy, Indonesia , Japan, Sweden, Greece and Switzerland by Colt Canada , Lithgow Arms , Beretta , Pindad , Sumitomo Heavy Industries , Bofors Carl Gustaf , and Astra Arms S.A. respectively. Copies of the Minimi have been produced for export by Norinco and made by Changfeng Machinery Co., Ltd in China without license, designated as CS/LM8  [ zh ] in 2011, and chambered in 5.56×45mm NATO . Another clone, known as

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1952-565: The US military has been carried out entirely in the US by a local subsidiary, FN Manufacturing LLC in South Carolina . As part of the US 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

2013-614: The United States and among NATO for the 7.62×51mm NATO cartridge. As of 2017 , it has been in use for over 60 years and is used on the Dillon M134D Minigun , M60 Machine Gun , FN MAG / M240 , Mk 48 , MG3 , HK21 , MG5 , UKM-2000 , K16 , SS-77 , and Negev NG-7 , among others. Some countries redesignated the M13 link when it was adopted. The M13 link replaced the older M1 links designed for .30-06 Springfield ammunition, which bound cartridges to each other at

2074-604: The XY 5.56, is made by Yunnan Xiyi Industry Company Limited. This was supposed to be mistaken for the CS/LM8 when news of the weapon was made in 2008. Taiwan also produced the Minimi without license, as the T75 . In addition, Egypt also produces the Minimi under license. The Minimi has been adopted by over 45 countries. Users include: Open bolt A firearm is said to fire from an open bolt or open breech if, when ready to fire,

2135-560: The airflow allowed into the chamber, action and barrel during pauses between bursts; moreover, unlike in the case of the closed-bolt format, the initial round in a burst is not introduced into the chamber until the moment before firing, and is thus only exposed to the residual heat for a fraction of a second. These two features combine to make open-bolt operation more suitable for weapons such as machine guns , which are intended to be capable of prolonged automatic fire. Open-bolt firearms also allow water drainage in underwater firearms . Firstly,

2196-566: The belt in place while loading. The handguard has three forward picatinny rails. A new bipod is 3-position height adjustable and seamlessly integrates into the shape of the handguard when folded back regardless of accessories that may be attached. Others features include a more ergonomic cocking handle and an optional heat shield, enabled by an added on long pin, to protect from barrel heat. The Minimi 7.62 Mk3 can be converted to fire 5.56×45mm rounds. Users that already have Minimi machine guns can partially or completely upgrade their existing weapons with

2257-408: The bolt (as is often done to keep the weapon clean when not in use). If one were to close the bolt (say by pulling the trigger and riding the bolt to the closed position), as soon as the bolt closes it will fire if a loaded magazine was left in the gun. This may be true with weapons utilizing a striker , but not with a weapon using a fixed firing pin , which relies on the momentum of the bolt to impart

2318-402: The bolt carrier back into a cocked position via the excess gas after the last round is fired. The exception to this is if the weapon is fully automatic and the trigger is held down after the last round was fired (and the gun does not have a "last round bolt hold open" mechanism) at which point the bolt will fly forward once more and stay there. In this case, the bolt merely needs to be retracted to

2379-422: The bolt closing also causes the fixed firing pin to strike a blow on the primer, without need for a separate hammer/striker and spring. In automatic weapons, an open bolt helps eliminate the dangerous phenomenon known as " cook-off ", in which the firing chamber becomes so hot that rounds spontaneously fire without trigger input. Open-bolt designs typically remain much cooler in operation than closed-bolt types due to

2440-482: The bolt retention mechanism may fail, resulting in a spontaneous discharge (i.e. without prior trigger input), with potentially dangerous consequences. Some simple submachine gun designs, such as the Sten , can discharge spontaneously when dropped onto a hard surface – even when uncocked – as the collision can jolt the bolt backward far enough that on returning it will pick up a round from the magazine, chamber it and fire it;

2501-417: The cartridge, and the round would be chambered, fired then extracted and ejected. The feeding pawl in the gun would pull the belt to the right as the gun was fired or cocked, sending the loose link out to the right side of the receiver, where the expended case was also ejected, normally separately from a different ejector port to the link. MIL-L-45403D stipulates that the force to strip a NATO approved round from

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2562-680: The current day, such as the H&;K MP5 series , have almost universally moved to closed-bolt designs for their practical advantages. Examples of mixed mode firearms (capable of operating from either an open bolt or closed bolt) include: Under United States federal law, fully automatic firearms are restricted under the National Firearms Act and other laws. In 1982, the Bureau of Alcohol, Tobacco, Firearms and Explosives ruled that certain semi-automatic open-bolt firearms manufactured after

2623-414: The danger of a round cooking off after extended periods of continuous fire, since a cartridge is only momentarily introduced into the chamber prior to ignition, and the movement of the bolt and bolt carrier forces air through the chamber and barrel after each shot, ventilating the barrel and removing heat. Gas escaping the gas cylinder is directed upward, avoiding kicking up dust and debris that would reveal

2684-593: The date of the rulings are to be treated as fully automatic because they were "designed to shoot" automatically. The aforementioned weapons are the KG-9 pistol, SM-10 pistol, SM-11A pistol, SAC Carbine, and the YAC Sten MK II. Around the time of these rulings, the manufacture of new open-bolt semi-automatic firearms became uncommon in the United States. The open bolt semi-automatic versions of certain guns are often as costly as their fully automatic counterparts. This

2745-410: The energy to ignite the primer . This is a common feature in basic submachine guns like the Sten gun or M3 "Grease Gun" , and even some machine guns . With a fixed firing pin, when the bolt is closed gently, without the momentum of the bolt closing at normal speed, there is not enough force imparted to the firing pin to ignite the primer. In this circumstance there will be a round in the chamber and

2806-502: The factory. In Australian service, the Minimi 7.62 is known as the "Maximi". In November 2013, FN Herstal unveiled the Mk3 version of the Minimi light machine gun the Minimi 5.56 Mk3 and the Minimi 7.62 Mk3. The Mk3 upgrades were based on operational experience and user feedback over the past 10 to 15 years. The stock is 5-position adjustable that is also adjustable for cheek rest height with a folding shoulder rest and hydraulic buffer. The feed tray has retaining pawls to hold ammunition from

2867-442: The feed cover and the front post secured to the barrel, closer to the muzzle end. An adapter can also be used that allows the use of standard NATO night and day sights. Standard equipment supplied with the Minimi consists of three ammunition boxes, a cleaning kit stored inside the forearm, lubricant bottle, sling and blank-firing barrel. The M249 version of the Minimi was adopted by the US military in 1982; since 1984, production for

2928-406: The gap in performance between open and closed bolt types. However, these designs are uncommon due to economics and complexity. Lastly, unless an ejection port cover is used, breech and action internals' exposure to the elements renders open-bolt designs universally vulnerable to contamination with dirt and dust through the open ejection port. Some versions of the open-bolt M3 submachine gun utilize

2989-430: The mainspring in readiness for firing the next round. In an open-bolt gun firing semi-automatically, the bolt is caught and held at this point by the sear after each shot; and in automatic open-bolt fire, it's caught and held in this manner whenever the trigger is released. In contrast to this, in closed-bolt guns, the trigger and sear do not affect the movement of the bolt directly. Generally, an open-bolt firing cycle

3050-613: The movement of the trigger, so, as explained above, if the weapon is dropped or if the sear becomes worn, the bolt can slam home, firing the weapon (although this issue is true to a degree in closed-bolt firearms as well). Closed-bolt designs are often used in rifles . The improved accuracy of closed-bolt weapons is more desirable, while the poorer heat dissipation is less of an issue for slower-firing weapons. In contrast, open-bolt designs are more often used in automatic weapons, such as machine guns . For fast-firing automatic weapons, heat will rapidly build up from sustained firing, but accuracy

3111-574: The neck, used on the older M1917 Browning machine gun and M1919 Browning machine gun family, though some conversions of the M1919 to the M13 were done, such as on the U.S. Navy Mark 21 Mod 0 machine gun, which saw service in the Vietnam War . Once converted, it cannot use other link types, as firearms made for the M13 Link are not backward-compatible with the M1 link (or other systems). The M9 link

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3172-427: The need for correspondingly heavier bolts as the chamber pressure increases. In simple blowback open-bolt designs, even in such relatively low-power calibers, the movement of the heavy bolt mass within the gun negatively affects aim and accuracy in two ways: While the latency is unavoidable with the open-bolt design, more sophisticated delayed-blowback open-bolt designs do allow for use of a lighter bolt, thus reducing

3233-460: The rearward position and does not return forward as is sometimes portrayed. Another feature of open-bolt designs is that the magazine simply needs to be removed to completely unload the weapon. A closed bolt requires the second step of cycling the action to remove the last round in the chamber (unless the weapon features an automatic hold-open device). It is essential to remove a loaded magazine before performing maintenance, or trying to cycle or close

3294-430: The risk is intrinsic to hand-held open-bolt guns unless safety features are included in the design. Another shortcoming of the open-bolt principle is that there is a brief delay between the trigger-pull and the firing of the cartridge because the (rather inert ) bolt has to move forward a significant distance between the two events. Since after the first shot an open-bolt firearm operates effectively indistinguishably from

3355-484: The sear mechanism; pushing the button to the right side exposes a red-coloured rim on the left side of the firearm and indicates the weapon is ready to fire. The black polymer pistol grip from the FAL and FNC rifles was initially used, but the Minimi is currently fitted with a modified grip with lateral grooves, installed at a smaller angle to the receiver. The Minimi features a welded receiver made from stamped steel . Both

3416-423: The shooter's position. The Minimi has a manually adjustable gas valve 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 spring extractor is located inside the bolt, while the tilting lever ejector

3477-401: The standard and Para variants are equipped with a fixed, 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 Minimi can also be fired from

3538-410: The two right-side loops of the next link, and which have a small metal tab that extends down to the cartridge base and fit into the extraction groove of the case. The M13 link binds the rounds from halfway down the length of the case to the case head. This was designed so that the bolt of the machine gun using the link would come forward upon squeezing the trigger and strip a round from its link from below

3599-423: The weapon to fire again, while a closed-bolt design has the additional step of the hammer striking the firing pin. Having a higher fire rate can be both an advantage and disadvantage depending on the situation. For handheld weapons, typically a lower rate of fire is desirable, as this will conserve ammunition and help keep the level of recoil more manageable. For vehicle-mounted weapons or fixed emplacements, however,

3660-489: Was originally used in the World War II -era MG 42 . The belt is moved in two stages during both the forward and rearward movement of the reciprocating bolt carrier, which provides for a smooth and continuous feeding cycle. The feeding mechanism top cover features a device that indicates the presence of a cartridge in the feed path. The barrels used in the Minimi have an increased heat capacity for sustained fire, feature

3721-584: Was used that enables the use of standard tactical accessories. Another variant of the SPW requested by the US Special Operations Forces is the Mk 46 Mod 0 that incorporates a lightweight fluted barrel but lacks the magazine feed system, vehicle mounting lugs and carry handle. A railed forearm ensures modularity and mission-adaptability permitting the use of flashlights, vertical grips, and infrared laser designators. An improved variant known as

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