Editing FN MAG (section)

==Design details==
{{more citations needed section|date=January 2013}}
{{multiple image
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   | footer    = The FN MAG is modeled on the Browning M1918 (BAR) and MG 42
   | image1    = FN_Browning_IMG_1533.jpg
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   | caption1  = <small>FN ''Mle D'' variant of the Browning M1918 (BAR)</small>
   | image2    = 20080809 mokotow 44 reenactment IMG 2617.jpg
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   | caption2  = <small>Wehrmacht [[Historical reenactment|reenactors]] with a belt-fed MG 42</small>
  }}

The MAG Model 60-20 is an automatic, air-cooled, [[gas-operated reloading|gas-operated]] machine gun, firing [[belt-fed]] [[7.62×51mm NATO]] from an [[open bolt]]. The MAG uses a series of proven design concepts from other successful firearms, for example the locking mechanism is modeled on that of the [[M1918 Browning Automatic Rifle#Belgium|Browning M1918 (BAR)]] [[automatic rifle]], which FN produced under license with some adaptions, and the feed and [[Trigger (firearms)|trigger mechanism]]s are from the [[World War II|WW II]]-era [[MG 42]] universal machine gun.<ref name="remtek.com"/>

===Operating mechanism===
[[File:GPMG components.JPG|thumb|left|A schematic showing the mechanism of the FN MAG.]]

The MAG operates via a [[Gas-operated reloading|long-stroke piston system]], which utilizes the ignited powder gases generated by firing vented through a port in the [[gun barrel|barrel]] to propel a gas piston rod connected to the locking assembly. The barrel breech is locked with a vertically tilting, downward locking lever mechanism that is connected to the bolt carrier through an articulated joint.

The locking shoulder and camming surfaces that guide the locking lever are located at the base of the [[receiver (firearms)|receiver]]. The unlocking sequence starts after {{convert|15|mm|in|1|abbr=on}} rearward gas piston rod movement to keep the breech block fully locked until the bullet has left the gun barrel and the high-pressure propellant gas pressure has dropped to a safe level.

The MAG fires from an [[open bolt]]. Both the spring-powered extractor and ejector are contained in the bolt. After firing, spent cartridge casings are removed downwards through an ejection port normally covered by a spring-loaded dust cover at the bottom of the receiver. The machine gun has a striker firing mechanism (the bolt carrier acts as the striker as it contains a channel that houses the firing pin, which protrudes out from the surface of the bolt upon firing), an automatic-only trigger assembly and a manual cross-bolt push-button [[safety (firearms)|safety]], which is located above the [[pistol grip]].<ref name="remtek.com">{{cite news|url=http://remtek.com/arms/fn/mag/|title=Belgium's MAGnificent MG|author=Kokalis, Peter G.|date=March 1985|work=Soldier of Fortune Magazine|access-date=2014-05-11|archive-url=https://web.archive.org/web/20140513011141/http://remtek.com/arms/fn/mag/|archive-date=2014-05-13|url-status=live}}</ref>

===Features===
[[File:FN MAG white background.jpg|thumb|right|Muzzle end of the MAG with rotary gas selector switch]]
The MAG's receiver is constructed from sheet metal stampings reinforced by steel plates and [[rivet]]s. The front is reinforced to accept the barrel nut and gas cylinder which are permanently mounted. Guide rails that support the bolt assembly and piston extension during their reciprocating movement are riveted to the side plates. The bolt's guide rails are shaped downward to drive the locking lever into engagement with the locking shoulder, which is also riveted to the side plates. The rear of the receiver has been reinforced and slotted to accept the butt stock.<ref name="remtek.com"/> The MAG is also equipped with a fixed wooden [[stock (firearm)|stock]] (later production models feature polymer furniture), pistol grip, and carrying handle.

A user-adjustable gas valve allows regulating the [[Rate of fire#Cyclic rate|cyclic rate of fire]] from 650 up to 1,000 rounds per minute, and subsidiary can adjust the gas system for various types of cartridge loadings or use in the presence of heavy fouling. A high cyclic rate of fire is advantageous for use against targets that are exposed to a general-purpose machine gun for a limited time span, like aircraft or targets that minimize their exposure time by quickly moving from cover to cover. For targets that can be fired on by a general-purpose machine gun for longer periods than just a few seconds, the cyclic firing rate becomes less important.

===Barrel===
The quick-change barrel has a slotted [[flash suppressor]]. The barrel's chamber and bore are [[Chrome plating#Hard|chrome-lined]] or [[stellite|stellite-lined]] for increased service life and the barrel has four right-hand grooves with a 305&nbsp;mm (1:12&nbsp;in) rifling twist rate. Also attached to the barrel is the front sight base, carry handle and gas block (equipped with an exhaust-type gas regulator valve with three settings).<ref name="remtek.com"/><ref>{{Cite web |url=http://www.usord.com/weapons/stellite |title=Stellite Lined Barrels |access-date=2021-09-22 |archive-date=2021-09-23 |archive-url=https://web.archive.org/web/20210923045006/http://www.usord.com/weapons/stellite |url-status=dead }}</ref><ref>{{Cite web |url=http://www.sadefensejournal.com/wp/torture-test-u-s-ordnance-mag-58m240/2/ |title=Torture Test: U.S. Ordnance MAG-58/M240 – Small Arms Defense Journal - Dan Shea - 28 February 2013 |access-date=22 September 2021 |archive-date=24 September 2021 |archive-url=https://web.archive.org/web/20210924180120/http://www.sadefensejournal.com/wp/torture-test-u-s-ordnance-mag-58m240/2/ |url-status=dead }}</ref> The barrel assembly weighs {{convert|3050|g|lb|2|lk=on|abbr=on}} and of the {{convert|630|mm|in|2|lk=on|abbr=on}} long barrel a portion of {{convert|487.5|mm|in|2|lk=on|abbr=on}} is rifled.<ref>{{Cite web|url=https://www.fnherstal.com/en/product/fn-mag|title=FN MAG®|website=www.fnherstal.com}}</ref> The MAG takes zero shifts between barrel assemblies into account by making the front sight of the assemblies adjustable with the help of tools.

===Feeding===
[[File:MG3 Zerfallgurt.jpg|thumb|left|M13 links reassembled to previously fired 7.62×51mm NATO cartridge cases]]
[[File:FN MAG 2.jpg|thumb|Ksp58B loaded with a non-disintegrating DM1 7.62mm ammunition belt in Lithuanian service]]

The weapon feeds from the left side from open-link, metal [[belt (firearm)|ammunition belts]]: either the American disintegrating [[M13 link|M13 linked belt]] ([[NATO]] standard) or the non-disintegrating segmented German DM1 belt, whose 50-round sections can be linked through a [[cartridge (firearms)|cartridge]]. The DM1 belt is based on the last version of the ''Gurt 34/41''-family used in World War II in MG 34 and MG 42 machine guns.<ref>{{Cite web|url=https://smallarmsreview.com/feeding-the-tiger/|title=FEEDING THE TIGER - Small Arms Review|date=March 1, 2005}}</ref> After firing, the separated M13 link or emptied DM1 belt section is cleared out on the right side of the receiver through an ejection port normally covered by a spring-loaded dust cover.<ref name="remtek.com"/>

In order to adapt the weapon to feed from one belt type to the other, several components of the feed mechanism need to be reconfigured since the position of the feed tray's cartridge stop and pawl angles in the top cover are different. The MAG features a pawl-type feeding mechanism that continues to move the feed link during both the rearward and forward cycles of the reciprocating bolt carrier, producing a smooth belt flow.<ref name="remtek.com"/>

The feeding mechanism's three pawls are actuated by a roller connected to the bolt carrier. The feed channel rail, feed link, both feed slides and the feed tray are [[chromium|chrome]] plated. The top cover body is an anodized [[aluminum]] [[casting (metalworking)|casting]]. In the infantry assault role, the weapon can be fitted with a [[sheet metal]] container that houses a 50-round belt and is attached to the left side of the receiver.<ref name="remtek.com"/>

===Sights===
[[File:Lichte mitrailleur, 7,62 mm NATO MAG, uitgerust met infra-rood richtapparatuur voor schieten bij verminderd zicht (2044 061257).jpg|thumb|left|An early infrared emitter and detector configured on the MAG for use in low visibility conditions.]]
[[File:Hastie in aslav.jpg|thumb|MIL-STD-1913 rail used to mount an optical sight atop the receiver]]

The MAG is equipped with [[iron sight]]s that consist of a forward blade (adjustable mechanically for both windage and elevation) and a folding leaf rear sight with an aperture in the down position for firing distances from {{convert|200|to|800|m|yd|0|lk=on|abbr=on}} in {{convert|100|m|yd|0|lk=on|abbr=on}} increments and an open U-notch for ranges from {{convert|800|to|1800|m|yd|0|lk=on|abbr=on}} graduated every {{convert|100|m|yd|0|lk=on|abbr=on}}. The rear sight is hinged to a base with protective ears that is integral with the receiver's upper forging. The iron sight line has a {{convert|848|mm|in|1|lk=on|abbr=on}} sight radius.

The top of later production model receivers often feature a [[Picatinny rail|MIL-STD-1913 rail]] as a mounting platform for firearm accessories like (low light) optical sights and [[night-vision device]]s.

===Safety===
With the safety placed in the ''safe'' setting, the [[sear (firearm)|sear]] mechanism is disabled. The safety can only be engaged with the weapon cocked.<ref name="remtek.com"/>

===Bipod and tripod===
[[File:Grondaffuit voor de Mitrailleur 7.62mm MAG (2009 D050713-X1080).jpg|thumb|left|The MAG tripod and cover as issued by the Royal Netherlands Army]]
[[File:De Mitrailleur 7.62mm MAG geplaatst op een grondaffuit (2009 D050713-X1083).jpg|thumb|right|MAG on tripod]]
For the light machine gun fire support role, the gun is fitted with a folding [[bipod]] (attached to the end of the gas cylinder) that can be adjusted for height. For carrying or use as a forearm, the aluminum legs can be folded back and secured in slots under the receiver by hooks and a spring-loaded catch. When firing from the hip, the bipod legs remain extended and the left leg is gripped for support. The bipod can be removed from the gas cylinder by tapping-out a roll pin in the gas cylinder head until it is flush and the bipod can be rotated enough to clear the gas cylinder's retaining lugs.<ref name="remtek.com"/>

In the static medium machine gun sustained fire support role, the weapon is mounted on a [[tripod]] that offers a higher degree of accuracy and control than the bipod, for example the FN 360° tripod, which features an elevation adjustment mechanism that enables the weapon's bore axis to be maintained from {{convert|300|mm|abbr=on|1}} to {{convert|600|mm|abbr=on|1}}, has a 30° to +15° elevation change and a 360° traverse range.