January 30, 2023
Much of the appeal of new guns like Ruger’s LC Carbine is found in the cartridge it fires. The small, bottlenecked cartridge is known for its high velocity, but what exactly is its purpose? In order to examine the 5.7x28mm cartridge, and why it is designed the way it is, we must turn the clock back to the Cold War and the looming shadow of possible Soviet invasion being cast over Europe. At this time, relatively lightweight personal body armor was becoming more prevalent among Soviet units. While these flak jackets were easily penetrated by 7.62x51mm and 5.56x45mm rifle fire, they were able to defeat conventional 9x19mm ball rounds. This in effect greatly diminished the effectiveness of 9x19mm service pistols and submachine guns. With Soviet body armor steadily improving, there was concern over 9mm weapons becoming ineffective.
Fabrique Nationale of Belgium recognized this growing threat and began working on a solution in the 1980s. NATO acknowledged the issue (in Doc D296) in 1990 when they officially began looking to replace the 9x19mm cartridge. Keep in mind, NATO members fielded a variety of pistols and submachine guns in 9mm which were issued to officers and support troops. The question though was what to replace the 9x19mm with? It took some six years of squabbling for NATO to finally define and agree upon just the performance and technical characteristics required from a system to replace the 1905 vintage 9mm.
As the ability to defeat body armor was the root of the issue, they first needed to define a standard for penetration. This led to the development of the “Collaborative Research into Small Arms Technology” (CRISAT) target which was standardized to allow penetration to be evaluated. This standard was defined in STANAG 4512 and consists of a 1.6mm Titanium (UK IMI Ti 318) plate with 20 layers of Kevlar (UK/SC/4468). It was intended to simulate the protection provided by body armor (such as the 6B3 vest) fielded by Warsaw Pact countries. While today Titanium plates may seem odd, they were widely used by the Soviets in protective armor. The CRISAT target stops standard 9x19mm ball ammunition, and any replacement for the 9mm would have to reliably penetrate this standard.
Any new cartridge would of course require a new firearm to fire it. NATO envisioned two types. One would be a traditional service pistol with an effective range of 50 meters. This would be carried in a traditional holster and could replace existing NATO member 9mm service pistols. The other type was to be some type of light automatic weapon. It was to weigh less than 6.6 pounds and have an effective range of 150 meters. It’s important to note this new weapon system was not envisioned for offensive use, like an assault rifle. Instead, it was intended for defensive use and was to be issued to troops whose primary duty was not fighting with a rifle, such as truck drivers, armored vehicle crewmen, and support personnel. Due to this, it was dubbed a “personal defense weapon” or PDW for short.
Fabrique Nationale has long been a leader in small arms development, and they did not shirk away from undertaking this project. To meet NATO’s needs, they developed two entirely new weapons, the P90 submachine gun and Five-seveN pistol. Both of these chambered a new proprietary 5.7x28mm cartridge developed specifically for this application. A relatively small bottlenecked round, it features a .224-inch diameter projectile loaded into a 1.138 inch (28.9mm) long case. Base diameter is 0.313 inch and overall length is 1.594 inches. The original prototype load was designated SS90, and it featured an ultralight 23-grain polymer-core projectile at approximately 2,800 fps from the P90. However, this projectile design did not prove satisfactory and it was replaced by a heavier load designated SS190 in 1994. This features a 31-grain .224-inch diameter armor piercing FMJ-BT projectile.
To provide the required penetration, and improve terminal performance, the SS190 projectile has a cone shaped steel penetrator in the nose with an aluminum core behind it. These are surrounded by a steel jacket. The design allows the projectile to be both relatively long, yet very light. It is designed to reliably penetrate a CRISAT target, and then yaw in soft tissue. Penetration in soft tissue is on the shallow side, 11 to 13.5 inches, reducing the chance of over penetration. With an overall length of only 40.5mm, the 5.7x28mm is substantially smaller than a standard 5.56 NATO round. At just 93 grains, it weighs about half of what a 9x19mm cartridge weighs.
Velocity of the SS190 load, from a P90’s 10.2-inch barrel, is a respectable 2,346 fps. Despite the high velocity, felt recoil is approximately 30% less than a 9x19mm NATO load thanks to the SS190’s lightweight projectile. Performance-wise, FN surpassed NATO’s request. When fired from a P90, the SS190 load will penetrate a NATO CRISAT target all the way out to 200 meters. It will even perforate a PASGT helmet at 275 meters. This load will penetrate a familiar Level IIIA vest, but it is not capable of penetrating a Level III hard plate.
While the SS190, which is color coded with a black tip, is the standard loading for the P90, FN also developed a number of specialty loads. These include the L191 Tracer, Sb193 Subsonic and SS192 JHP. The L191 Tracer drives a 31-grain projectile at identical listed velocities as the SS190. It features a red color code on the projectile. The Sb193 Subsonic loading drives a 65-grain projectile at 1,049 fps from the P90 and is intended for use with a sound suppressor. It is identified by a white color code on the projectile. The SS192 featured a 28-grain JHP and was designed for training, to save wear and tear on steel targets. It is no longer imported into the US.
While the P90 and its 5.7x28mm cartridge were recommended for adoption by NATO, internal politics have prevented this from happening. Despite this, it has gone on to be adopted by a number of counterterrorist, special forces and law enforcement units around the world, including the U.S. Secret Service. It gained some notoriety when deployed during the Japanese Embassy raid in Lima Peru in 1997. During this assault a 5.7x28mm round from a P90 penetrated the terrorist ringleader’s body armor, killing him.
Since its introduction, the 5.7x28mm cartridge has gained a very dedicated following on the US commercial market. Many appreciate its accuracy, mild recoil, flat trajectory and high velocity. The cartridge does have a number of fine points. However, it would be nice if there were more loads available, especially economical practice ammunition. That is perhaps the one thing most shooters would like to see, an economical 5.7x28mm load available in bulk. Even so, fans of the 5.7x28mm cartridge tend to like it very much indeed.
About the Author
David M. Fortier has been covering firearms, ammunition and optics since 1998. He is a recipient of the Carl Zeiss Outdoor Writer of the Year award and his writing has been recognized by the Civil Rights organization JPFO. In 2007 he covered the war in Iraq as an embedded journalist.
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