HK MR556 A4 SBR is HK‑USA’s commercial variant of the HK416 with a short‑stroke gas piston system for improved reliability and reduced carbon fouling. Features an adjustable gas regulator, ambidextrous controls, and a lighter, slimmer profile. SPECIFICATIONS Caliber: 5.56 x 45mm Barrel Length: 11 in Overall Length: 27.9 in – 31.7 in Overall Height: 7.5 in Overall Width: 3.07 in Weight: 7.67 lb (without magazine) Capacity: 10 rd