M855

M855 M855 is a 5.56×45mm NATO cartridge widely adopted by United States Armed Forces, NATO, and numerous law enforcement and civilian users. Developed during the late Cold War era, it introduced a steel penetrator in a boat-tail projectile to improve penetration against hard targets and barriers compared with earlier rounds used in Vietnam War and later conflicts. The cartridge has been central to debates about terminal performance, armor penetration, and international regulation, involving organizations such as NATO Standardization Office, North Atlantic Treaty Organization, ATF, and national militaries.

Design and development

The M855 was developed at Picatinny Arsenal and standardized in the 1980s through coordination with NATO Standardization Office and U.S. Army Materiel Command to meet requirements emerging from lessons learned during the Vietnam War and advances in small arms in the Cold War. Designers sought to improve upon the earlier 55-grain projectiles used in the M16 rifle and to address threats posed by steel and light armor encountered in potential conflicts with forces using equipment from Warsaw Pact states like Soviet Union and People's Republic of China. The projectile features a lead core with a steel penetrator tip and a gilding metal jacket, incorporating a boat-tail and cannelure influenced by earlier designs from FN Herstal and developmental work at Aberdeen Proving Ground and Edgewood Arsenal. Engineering coordination involved institutions such as U.S. Army Research Laboratory, Lawrence Livermore National Laboratory, and procurement oversight by Defense Logistics Agency.

Specifications

The M855 projectile weighs approximately 62 grains and is seated in a 5.56×45mm NATO case compatible with chamberings specified in NATO EPVAT and STANAG 4172. Typical muzzle velocities vary with barrel length—carbine-length barrels like the M4 carbine produce lower velocities compared to rifles such as the M16A2 or M16A4—with manufacturer and lot variations overseen by contractors including Fiocchi Munizioni, Lake City Army Ammunition Plant, and international producers licensed under NATO agreements. The projectile geometry includes a 16-grain steel penetrator at the tip, a lead core, and a boat-tail to stabilize long-range flight; specifications reference ballistic testing protocols at facilities like Aberdeen Proving Ground and Picatinny Arsenal and comply with standards used by U.S. Army Marksmanship Unit and NATO interoperability tests.

Performance and terminal effects

Terminal behavior of the M855 has been analyzed in testing at Edgewood Arsenal, Oak Ridge National Laboratory, and independent laboratories associated with institutions such as Ballistics Research Laboratory and Sandia National Laboratories. At typical engagement ranges, the steel penetrator improves performance against steel plate and certain types of light cover compared to 55-grain projectiles adopted after World War II, but results vary with impact velocity, yaw, and intermediate barriers like automotive glass, sheet metal, or concrete analyzed in experiments coordinated with U.S. Marine Corps Schools and U.S. Army Infantry School. Wounding mechanisms documented in forensic and medical literature from Walter Reed National Military Medical Center and civilian trauma centers reference temporary cavity, fragmentation under specific conditions, and the influence of yaw induced by barrel twist rates standardized in service rifles such as the M16 and M4. Comparative assessments cite other cartridges and projectiles developed by manufacturers like FN Herstal, Remington Ammunition, and research collaborations with Johns Hopkins University trauma researchers.

Operational use and variants

M855 has been fielded in rifles and light machine guns including the M16A2, M16A4, M4 carbine, M249 SAW, and exported platforms used by NATO member states such as the United Kingdom, Germany, France, Italy, and Canada. Variants and evolutions include tracer-loaded versions paralleled by developments like the M856 tracer, lead-free alternatives driven by environmental and training regulations influenced by institutions like Environmental Protection Agency and Department of Defense initiatives, and improved performance rounds such as the M855A1 developed in response to performance requirements after engagements in Iraq War and War in Afghanistan (2001–2021). Production and procurement involve industrial partners including FN Herstal, Olin Corporation, Northrop Grumman, and contract management through Defense Logistics Agency and U.S. Army Contracting Command.

Controversies and legal/regulatory status

M855 has been the subject of international debate regarding compliance with protocols like the Hague Conventions and national policy discussions in legislatures such as the United States Congress and parliaments of European Union member states. Litigation and regulatory review by agencies including the Bureau of Alcohol, Tobacco, Firearms and Explosives, Department of State, and the European Court of Human Rights-adjacent discourse have intersected with procurement decisions by ministries of defense in countries like Poland, Turkey, and Israel. Debates over terminal effects, armor penetration, environmental lead content, and use in law enforcement have involved standards bodies such as NATO Standardization Office and testing by forensic institutions like FBI Ballistics Laboratory and National Institute of Justice. Public advocacy and NGOs including Human Rights Watch and Amnesty International have engaged in discourse about small arms policy that touches on ammunition types adopted by militaries and police forces.

Category:5.56×45mm NATO cartridges