M193

M193
Name	M193
Origin	United States
Designer	Remington Arms/Ballistic Research Laboratory
Design date	1970s
Produced	1970s–present
Parent	5.56×45mm NATO (commercial derivation)
Case type	Rimless, bottleneck
Bullet diameter	0.224 in (5.7 mm)
Neck diameter	0.253 in (6.43 mm)
Shoulder diameter	0.362 in (9.19 mm)
Base diameter	0.378 in (9.60 mm)
Rim diameter	0.378 in (9.60 mm)
Case length	1.760 in (44.70 mm)
Overall length	2.260 in (57.40 mm)
Primer	Small rifle primer
Max pressure	55,000 psi

M193

M193 is a 5.56×45mm commercial small-arms cartridge originally developed in the United States in the 1970s for use in lightweight rifles and carbines. It served as a common chambering in many Vietnam War-era and post‑Vietnam service weapons, influencing adoption decisions by United States Armed Forces, NATO, and civilian manufacturers such as Colt's Manufacturing Company, FN Herstal, and Armalite. Its characteristics shaped ammunition development debates involving agencies like the Ballistic Research Laboratory and contractors including Remington Arms and Winchester Repeating Arms Company.

Development and Design

The cartridge emerged from cooperative research among the United States Army ordnance researchers, the Ballistic Research Laboratory, and private firms like Armalite and Colt's Manufacturing Company to produce a lightweight, high‑velocity round suitable for intermediate‑range engagements. Testing programs contrasted it with full‑power cartridges used by M14 rifle and influenced doctrine in the United States Marine Corps and United States Army Special Forces. Designers sought to balance terminal performance, controllability in automatic fire, and logistics compatibility with 5.56×45mm NATO standardization efforts involving NATO committees and ballistics laboratories in United Kingdom and Germany. Adoption decisions referenced trials involving weapons such as the M16 rifle, AR-15, FN FNC, and HK33.

Technical Specifications

M193 uses a 55‑grain full metal jacket boattail or soft‑point projectile with a .224‑inch diameter, seated in a 1.760‑inch case within a 2.260‑inch overall length compatible with standard 5.56×45mm chambers. It is loaded to a maximum average pressure near 55,000 psi as measured by SAAMI methods and employs a small rifle primer typical of commercial cartridges from firms like Federal Premium Ammunition and Remington Arms. Cartridge dimensions conform closely to the original commercial 5.56×45mm specification that paralleled NATO technical protocols negotiated among member states including France, Italy, and Canada.

Ballistics and Performance

Typical muzzle velocity for a 55‑grain projectile from a 20‑inch test barrel is approximately 3,250 feet per second, producing muzzle energy near 1,290 foot‑pounds—figures referenced in comparative trials alongside rounds such as 7.62×39mm used in the AK‑47 and 5.45×39mm used in the AK‑74. At 300 meters the retained velocity and energy decline predictably, influencing engagement policy in units such as United States Army Rangers and U.S. Marine Corps Force Reconnaissance. Terminal effects and yaw/fragmentation behavior in soft targets were examined by research teams at the Edgewood Arsenal and by forensic studies tied to law enforcement agencies like the FBI and ATF.

Operational Use and Ammunition Types

M193 was fielded widely in service rifles including the M16A1, early AR-15 variants, and carbines issued to units such as 101st Airborne Division and 82nd Airborne Division. Ammunition variations include full metal jacket boat‑tail, tracer, blank, and specialty loadings developed by manufacturers like Winchester Repeating Arms Company and Federal Cartridge Company for training, combat, and marking purposes. Law enforcement agencies including the Los Angeles Police Department and New York City Police Department evaluated 55‑grain loadings for patrol rifles, while special operations units compared M193 to heavier projectiles for barrier penetration and terminal effects, alongside developments like the 62‑grain NATO SS109 round standardized later by NATO.

Compatibility and Firearms Chambered For M193

Chambering that accepts this cartridge includes rifles and carbines from makers such as Colt's Manufacturing Company, ArmaLite, FN Herstal, Heckler & Koch, Bushmaster Firearms International, Smith & Wesson, and Ruger. Platforms include the M16 family, AR‑15, HK33, FAMAS (in commercial variants), and select export models from Steyr Mannlicher. Civilian sporting rifles and competition firearms from companies like Daniel Defense and LaRue Tactical also list compatibility with 5.56‑standard ammunition including this load.

Variants and Related Cartridges

Related cartridges and developments include the 5.56×45mm NATO SS109/M855 adopted by NATO; earlier commercial progenitors from ArmaLite and Remington; and later specialized loads such as 62‑grain, 77‑grain, and frangible rounds made by Black Hills Ammunition, Federal Premium Ammunition, and Hornady. Competing intermediate cartridges in global service include 7.62×39mm, 5.45×39mm, and experimental rounds tested by agencies like DARPA and research institutes in Sweden and Switzerland.

Safety, Handling, and Legal Considerations

Safe handling follows manufacturer guidelines set by firms like SAAMI and standards referenced by military publications from the Department of Defense. Ammunition storage, transportation, and proof testing align with procedures used by arsenals such as Watervliet Arsenal and Rock Island Arsenal and with regulatory oversight by agencies including the Bureau of Alcohol, Tobacco, Firearms and Explosives. Legal considerations for civilian possession and use are governed at state levels (for example, laws in California, New York (state), and Texas) and by federal statutes enforced by Bureau of Alcohol, Tobacco, Firearms and Explosives and interpreted in court decisions involving United States District Court cases.

Category:Cartridges