...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 key idea 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-H Sniper variant, 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). 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.
It is still unclear if the SCAR system will have quick detachable barrels for various configurations and lengths (from short-barreled CQC to long-barreled SV), or the barrels will be swapped along with entire upper receiver. The SCAR-H system also will have different type lower receivers, adapted to various types of ammunition and various types of magazines (i.e. 7.62mm NATO magazines and 7.62 M43 AK-type magazines, respectively). SCAR-L rifle will use improved M16-type magazines.
The trigger unit with ambidextrous safety-fire mode selector switch will allow for single shots and full automatic fire, apparently with no provisions for limited-length bursts mode. The charging handle could be easily installed on either side of the weapon, so the upper receiver has respective cuts on both sides. Top of the upper receiver is covered by the full-length integral Picatinny rail (MIL-STD 1913); additional Picatinny rails are mounted on both sides and below the handguards. Side-folding polymer buttstock is adjustable for length of pull, and is shaped to proved positive cheek rest. SCAR rifles apparently will be fitted with removable, adjustable iron sights, with folding diopter-type rear sight on the receiver rail, and folding front sight on the gas block. Any additional type of sighting equipment, necessary for current tasks, including telescope and night sights, can be installed using MIL-STD 1913 compatible mounts. Current prototypes of SCAR rifles do not have bayonet mounts, and, probably, will never have one.