MIL-C-63990B, MILITARY SPECIFICATION: CARTRIDGE 5.56mm, TRACER, M856 (18-APR-1986) [S/S BY MIL-DTL-63990D (CONTROLLED DISTRIBUTION)]

MIL-C-63990B, MILITARY SPECIFICATION: CARTRIDGE 5.56mm, TRACER, M856 (18-APR-1986) [S/S BY MIL-DTL-63990D (CONTROLLED DISTRIBUTION)]., This specification covers the requirements, examinations and tests for the M856 Tracer cartridge for, use in 5.56mm weapon systems with a “one in seven” (one revolution in seven inches) barrel twist (see 6.1).