The US Special Operations Command(US SOCOM) issued a solicitation for the procurement of SOF CombatAssault Rifles (SCAR)on October 15th, 2003. This solicitation requested a new combat rifle,specially tailored for the current and proposed future needs of the US Special Forces,which are somewhat different from latest generic US Army requirements,which are being fulfilled by the newest Heckler-KochXM8 assault rifle. The key difference in basic requirements between XM8 and SCAR is that, while XM8 is a single-caliber weapon system, tailored for 5.56x45mm NATO ammunition, the SCAR should be available in various different calibers.Initial SOF requirements included two basic versions of SCAR system - the SCAR Light (SCAR-L), available in 5.56mm NATO, and the SCAR Heavy (SCAR-H), which should be initially available in significantly more powerful 7.62x51 NATO chambering, and should be easily adaptable in the field to other chamberings. These other chamberings initially include the well-spread 7.62x39 M43 ammunition of the Soviet / Russian origins, and probably some others (like the proposed 6.8x43 Remington SPC cartridge, especially developed for US Special Forces).The keyidea of SCAR rifle system is that it will provide the Special Forces operators with wide variety of options, from short-barreled 5.56mm SCAR-L CQC variation,tailored for urban close combat, and up to long range 7.62x51 SCAR-HSnipervariant, as well as 7.62x39 SCAR-H, which will accept "battlefield pickup" AK-47/AKM magazines with 7.62 M43 ammunition, available during the operations behind the enemy lines. Both SCAR-L and SCAR-H shall be initially available in three versions, Standard(S), Close Quarters Combat (CQC) and Sniper Variant(SV; now it is dubbed Long Barrel - LB). All these variants, regardless the caliber and exact configuration, will provide the operator with the same controls layout, same handling and maintenance procedures, and same optional equipment, such as sights,scopes, and other current and future attachments.
Late in 2004 USSOCOM announced, that the winner for the initial SCAR contracts is the FN USA, an US-based subsidiary of the famous Belgian company Fabrique Nationale Herstal. prototype rifles were manufactured by FN Manufacturing Inc, US-based subsidiary to FN Herstal;