Specifications
Weight 2.27 kg–3.9 kg (5.5–8.5 lb)
Barrel length
From 6.5 inches (170 mm) to 24 inches (610 mm)
20 inches (510 mm) (standard)
16 inches (410 mm) (civilian standard)[1]
14.5 inches (370 mm) M4 Military Standard
Cartridge 5.56×45mm NATO and others; see list of AR platform calibers
Action Direct impingement or Gas Piston[2] / Via a Rotating bolt
Blowback on pistol-caliber variants
Effective firing range ~550 metres (600 yd)[3]
Feed system Detachable or integral magazine, 5.56mm / .223 Remington versions use STANAG magazines
Belt feed in some versions
Sights Adjustable front and rear iron sights