STANAG magazine
Production of the 30-round magazine started late 1967 but did not fully replace the 20-round magazine until the mid-1970s. Standard USGI aluminum 30-round M16 magazines weigh empty and are long. The newer plastic magazines are about a half-inch longer. The newer steel magazines are about 0.5-inch longer and four ounces heavier. The M16's magazine has become the unofficial NATO STANAG magazine and is currently used by many Western nations, in numerous weapon systems.