The FNAC is chambered in NATO 5.56x45mm like the SCAR-L and civilian SCAR-16s, but the FNAC has some significant differences. The barrel is 14” long, 0.5” shorter than the SCAR-L STD and 2.5” shorter than the SCAR-16s. Compared to both the L and 16s the FNAC has removed the integrated front sight from the gas block and put a traditional folding front sight on the picatinny rail.

FN Herstal USA’s latest SCAR variant the FNAC (FN Advanced Carbine) has been proposed for the US Army Individual Carbine competition. The Individual Carbine was a carbine competition that was to select the planned successor to the M4 carbine in the United States Army.

The Individual Carbine was to provide accurate and reliable firepower. It had to be capable of semi-automatic and full-automatic fire. Integrated rails were to accept MIL-STD-1913 Picatinny rail-mounted accessories. It had to be fully ambidextrous. While the caliber for any new weapon was open for the competition, any contributions not of 5.56×45mm NATO and/or 7.62×51mm NATO had the burden of test ammunition and extra costs placed on the competitor. The draft asked for a non-developmental weapon. Rather than working with the Army to develop a new weapon, competitors were to bring forward designs they already had available.

Weapons submitted included the XCR by Robinson Armament Co., an off-the-shelf or derivative of the M6A4 by LWRC, the ACR by Remington, the SR-16 by Knight's Armament Company, the FN SCAR by FN Herstal, the CM901 by Colt's Manufacturing Company, and the HK416 by Heckler & Koch. A draft request for proposal (RfP) was issued in late 2010 followed by an industry day. The finalized RfP was issued in second quarter FY 2011 to which industry had a month to respond.