Emerging from the U.S. military’s FN SCAR® program, the MK 16 and MK 17 weapon systems use a common multi-caliber architecture that is highly modular and instantly adaptable to virtually any mission requirements, and is further enhanced by the MK 13 grenade launcher.

Since its adoption of the AR15 by the U.S. Air Force in 1962, and by the U.S. Army in 1964, the basic individual military weapon of the United States has demonstrated certain compromises inherent in its design and cycle of operation.

Foremost among these compromises is the direct-gas impingement operation system. During the firing and ejection cycles, substantial amounts of carbon and other by-products of cartridge combustion are routed directly into the bolt and receiver areas, causing increased fouling. Naturally, this increased fouling results in reduced operating reliability and requires greater frequency of cleaning and other maintenance by the weapon operator.

Responding to concerns from special operators in combat regarding the reliability, accuracy, safety and ergonomics of the current platform, the Naval Surface Warfare Center, Crane, began an investigation of potential improvements. In the years that followed the U.S. Government conducted an Analysis of Alternatives (AoA) to determine if enhancements or upgrades could be made to the existing platform, or if a new weapon was needed. It was determined that a new, more reliable and more adaptable individual weapon was required.

In late 2003, the Joint Operational Requirements Document for a new combat assault rifle was approved and signed; the following January, a worldwide solicitation was issued to the military firearms industry.

In July 2004, in a full and open competition, nine vendors submitted twelve different designs for the three new weapon systems. Unlike the competition, FN delivered a new weapon built to the operator’s requirements—not adapted to them. The FN SCAR® submission passed all of the GO/NO-GO criteria and was unanimously chosen by the selection board composed of senior SOF operators representing every selection component. In November of the same year, FN was awarded the full FN SCAR® contract for both 5.56mm and 7.62mm rifles, along with the 40mm Enhanced Grenade Launcher Module (EGLM).

Developmental testing by FN designers, engineers and operators from various branches of the U.S. Military to evaluate the new weapons’ endurance, reliability and accuracy was conducted from August 2005 through January 2006. Four Early User Assessments were also conducted prior to, during and after the developmental testing process to integrate operator feedback into the final FN SCAR® design.

FN SCAR® Principle of Operation


The MK 16 and MK 17 rifles operate on the short-stroke gas piston system. As the bullet passes the gas port in the barrel a portion of the propellant gases are routed through the gas regulator to the gas piston located below the front sight post. The gas pushes rearward against the piston, which drives the moving parts assembly rearward to eject the fired case and load a new cartridge from the magazine. Excess gases are vented forward through the gas vent hole in the front of the gas regulator. The advantage over the direct gas impingement system is that heat, soot and carbon from propellant combustion are not routed into the bolt or chamber, keeping these critical areas cooler and cleaner for greater reliability and enhanced accuracy. When compared to a direct gas impingement system that has been adapted to use a gas piston or operating rod, the FN SCAR® gas system proves to be more simple, robust and reliable. The first position on the gas regulator is for normal operation, while the second position ensures there is no increase in the cyclic rate of fire when using a sound suppressor.

Low-Rate Initial Production (LRIP) and Production

Acceptance Test and Evaluations were conducted from May 2006 through June of 2007. Beginning in August 2007, the Initial Operational Test and Evaluation phase was conducted by various units of the U.S. Military community, including the U.S. Army Rangers, U.S. Marine Corps Special Operations Command, U.S. Navy SEALS and U.S. Army Special Forces. These tests were carried out in a variety of operational environments including urban, maritime, jungle and winter/mountain warfare situations.

Final testing was completed in September of 2008 and the FN SCAR® and EGLM were announced as Operationally Effective/Operationally Suitable and Sustainable (OE/ OS). Initial fielding to operational units with U.S. special operators began in April 2009. The first operational units armed with the FN SCAR® system deployed for overseas duty in the summer of 2009.

In April 2010, upon successful in-theater combat assessments, the FN SCAR®(MK 16 and MK 17) and the EGLM (MK 13) were granted Milestone C (the acquisition phase associated with fielding/deployment). In August of the same year the FN SCAR® system received approval for full-rate production for the MK 16, MK 17 and MK 13.