The AR-15 is a versatile platform with numerous variations, each designed for specific applications. There are three main types of AR-15. The AR-15 Rifle is the standard type, typically featuring a barrel length of 16 to 20 inches. The AR-15 Carbine is a shorter version of the standard rifle, usually with a barrel length of 14.5 to 16 inches. AR-15 Pistols are the smallest configuration, generally featuring a barrel length of less than 12 inches.