Manufactured in 1964 the first year of production as a civilian equivalent to the M16 being fielded in the jungles of Vietnam. The SP-1 was designed by Colt after seeing the desire of shooters and hunters alike for a semi-automatic rifle chambered in the popular .223 Remington cartridge. The rifle's light weight made it a popular choice for hunters across the nation. The rifle has all of the features of the early SP1 rifles including a three prong flash hider on the pencil profile barrel, ventilated triangular forearm, A1 length buttstock, and "slab sided" receiver set with integral carry handle. The bolt carrier is properly smooth sided, with a flat end to the retention pin, and a chrome plated bolt marked "P". A two-piece buffer is also present. The left side of the lower receiver is marked with the standard Colt markings as well as the three digit serial number. The foundation laid by the SP-1 is found for the AR-15 platform of rifle which has become the most popular rifle in the United States, while also having a lineage that stretches from the jungles of the Vietnam War to the deserts of the Global War on Terror.