A STANAG magazine is a type of detachable firearm magazine proposed by NATO in October 1980, used in the SA80 and L98A1 rifles.
Shortly after NATO's acceptance of the 5.56x45mm NATO rifle cartridge, Draft Standardization Agreement (STANAG) 4179 was proposed in order to allow the military services of member nations easily to share rifle ammunition and magazines during operations, at the individual soldier level, in the interest of easing logistical concerns. The magazine chosen for this standard was originally designed for the U.S. M16 rifle. Many NATO member nations, 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'.
STANAG-compatible magazines can be made to almost any capacity, though those used for military service usually hold 20 or 30 rounds of 5.56x45mm NATO ammunition. 40 and 50-round box magazines as well as 90-round drum magazines and 100-round Beta C-Mag drum magazines designed to comply with STANAG 4179 have also been manufactured.
The STANAG-compatible box magazine, while relatively compact compared to other types of 5.56x45mm NATO box magazines, has often been criticized for a perceived lack of durability and a tendency to malfunction if not treated with a level of care that often cannot be afforded under combat conditions. Because STANAG 4179 is only a dimensional standard, production quality from manufacturer to manufacturer is not uniform. Magazines have been manufactured with lightweight aluminum or plastic bodies and other inexpensive materials in order to keep costs down, or to meet requirements that treat the magazine more as a disposable piece of equipment than one that is supposed to stand up to repeated combat use.
These problems have been addressed by several manufacturers, most notably Heckler & Koch, who designed a new 30-round STANAG-compatible box magazine during their contract to rebuild and improve the SA80 rifle for the United Kingdom. As a result, several manufacturers now offer improved STANAG-compatible magazines as well as high-grade stainless steel bodies, rust- and set-resistant chrome-silicon springs, and anti-tilt followers as upgrade components for existing STANAG magazines.