The ArmaLite AR-18 was developed as a piston-operated alternative to the AR-15 that could be manufactured with less precision tooling, making it suitable for production in developing nations. Adopted in limited numbers, the AR-18 operating system of short-stroke gas piston with dual guide rods became highly influential, directly influencing the design of the HK G36, SA80, and other modern rifles. Type: Rifle Action: Semi-Automatic/Full-Auto Caliber: 5.56x45mm NATO Capacity: 20 Year introduced: 1963, USA Weight: 6.7 oz Overall length: 38.5" Status: Discontinued Military use: Yes Intended use: Military