A STANAG magazine^[1][2] or NATO magazine is a type of detachable firearm magazine proposed by NATO in October 1980.^[3] Shortly after NATO's acceptance of the 5.56×45mm NATO rifle cartridge, Draft Standardization Agreement (STANAG) 4179 was proposed in order to allow NATO members to easily share rifle ammunition and magazines down to the individual soldier level. The U.S. M16 rifle's magazine proportions were proposed for standardization. Many NATO members, but not all, subsequently developed or purchased rifles with the ability to accept this type of magazine. However, the standard was never ratified and remains a "Draft STANAG".^[4]

The STANAG magazine concept is only an interface, dimensional and controls (magazine latch, bolt stop, etc.) requirement.^[2][5] Therefore, it not only allows one type of magazine to interface with various weapon systems,^[2][5] but also allows STANAG magazines to be made in various configurations and capacities.^[2][5] The standard capacities of STANAG-compatible magazines are 20 or 30 rounds of 5.56×45mm NATO ammunition. There are also 5-, 10-, 40- and 50-round box magazines,^[5] as well as 60- and 100-round casket magazines,^[6][7] 90-round snail-drum magazines,^[8] and 100-round drum magazines.^[9]

The STANAG magazine, while relatively compact compared to other types of 5.56×45mm NATO box magazines, has often been criticized for a perceived lack of durability and a tendency to malfunction unless treated with a level of care that may not be practical under combat conditions. Because STANAG 4179 is only a dimensional standard, production quality from manufacturer to manufacturer is not uniform.

As a result, in March 2009, the U.S. military began to accept delivery of improved STANAG magazines.^[10] To increase reliability, these magazines incorporate heavier, more corrosion resistant springs and new tan-colored anti-tilt followers.^[11]

ARDEC began development of a new magazine design in July 2013 to address feeding issues of older designs with the new M855A1 Enhanced Performance Round. It was first made public in 2014 and completed development in mid-2016 as the Enhanced Performance Magazine. The magazine uses a blue follower and a tan body which presents the rounds with a better angle to the weapon's feedway, preventing the hardened steel tip of the EPR from contacting the aluminum feed ramp of the M4 carbine, increasing mean rounds between stoppage by 300%.^[12][13]

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  Standard issue 30-round M16 magazine.
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  Loaded STANAG magazines
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  Close-up of loaded STANAG magazine
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  Improved M16 magazine follower
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  USGI Enhanced Performance Magazine (EPM) magazine for AR-type rifles^[14]
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  The Feed Lips Wear Tool is designed for inspecting STANAG magazines
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  T91 30-round STANAG-compliant magazine with ammo capacity indicator.
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  STANAG-compliant 30-round PMAG with Ranger Plate from Magpul Industries. Note: clear viewing window.
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  Diagram of a STANAG Beta C magazine
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  In order to comply with civilian legal restrictions. STANAG 30-round magazines may be pinned to hold only 5 rounds.
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  Two STANAG 30-round magazines placed together with duct tape in the "Jungle style".
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  Ditto, with an improvised pull tab.

Over the years different cartridges that fit into the STANAG magazine emerged, some rounds like .300 AAC Blackout have the same rim diameter as .223 Remington and only require a barrel change to be used in a firearms that was previously using in .223 Remington.

Loading a STANAG magazine, particularly one with a large capacity and a corresponding high spring pressure pushing the rounds to the top of the magazine, can be quite difficult. A number of devices are available to make this task simpler. These are sometimes called speedloaders but are more commonly known as magazine loaders, stripper clips, spoons, or stripper clip guides. There are a wide range of both commercial and military type loading tools available for STANAG magazines. For example; draft STANAG 4181 is a type of stripper clip and guide tool proposed for standardization based on the USGI M16 rifle stripper clips and guide tools.^[24]

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  Manually loading a magazine with individual rounds.
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  STANAG guide tools and stripper clip filled with 5.56mm NATO ammo.
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  Close-up of STANAG loading guide tool.
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  Loading a magazine with STANAG stripper clip and guide tool.
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  Ditto, with stripper clip pressed against a hard surface to load the magazine more quickly.
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  Loading a magazine with loading tool.
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  Loading a magazine with an alternative style of loading tool.
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  M-16 / AR-15 LULA magazine loader and unloader.
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  StripLULA™ loading tool.
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  BenchLoader heavy-duty magazine loader.
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  Trijent Mech-loader for high volume loading

• The "RAM-LINE 30-round COMBO MAG" is a uniquely notable STANAG magazine. These commercial translucent plastic magazines can be used in both AR-15 type rifles and Ruger Mini-14 type rifles.^[25]
• Magnolia States Armory offers an adapter that allows the use of STANAG magazines in 5.56mm Galil rifles as well as one that works in a variety of 5.56mm AK-47 type rifles such as the Saiga, WASR3 and Norinco rifles.
• While STANAG magazines are typically loaded with 5.56 mm NATO ammo, they are also used for other calibers as well.
• There are also a wide range of dummy STANAG magazines in a variety of sizes, weights and colors for training purposes.

• SR-25 pattern magazine, a scaled up version of the STANAG magazine for .308 based cartridges.