The M27 link, formally Link, Cartridge, Metallic Belt, 5.56mm, M27 is a metallic disintegrating link issued by the United States armed forces and among NATO and designed for use in belt-fed firearms. It holds 5.56×45mm NATO ammunition. It was first developed for the Stoner 63 belt-fed light machine gun/squad automatic weapon in Vietnam but was later resurrected and adapted for use with the FN Minimi LMG / M249 SAW. It It is a scaled-down version of the M13 link and used on the FN Minimi/M249, HK21, MG4, CETME Ameli, K3, Mini-SS and Negev, among others.
Each M27 link consists of a single piece of metal curved into two partial cylinders, into which adjacent rounds slide. Like the M13 link, the M27 link is a push-through design. Rounds are extracted by pushing forward out of the link. With the round freed, the link disintegrates (detaches from the belt) and is ejected. This is in contrast with older belt systems which were typically made of fabric and were fed straight through the weapon without disintegrating. MIL-L-63532C stipulates that the force to strip a NATO approved round from the M27 link should be between 5.5 and 16 lbf (24.5 and 71.2 N) and the belt should have a minimal tensile strength of 33 lbf (146.8 N). A single M27 link weighs approximately 2 g (30.9 gr).
The links often have an extra anti-corrosion surface treatment, generally black phosphate, and can be collected and reassembled by hand with fresh ammunition, but in practice this is not commonly done as it is labor-intensive, and the inexpensive links are considered disposable.