The Colt SP1 was the first commercially available, civilian-legal semi-automatic version of the military M16/AR-15 platform. Introduced by Colt in 1964 and produced until the late 1980s, it serves as the foundational "retro" rifle for civilian AR-15 collectors. Core Technical Specifications Caliber: .223 Remington / 5.56x45mm NATO Action: Direct gas impingement, rotating bolt, semi-automatic only Barrel Length: 20 inches (standard rifle configuration) featuring a lightweight "pencil-thin" profile Overall Length: 38.58 inchesWeight: 6.95 lbs (approx. 3.15 kg), which is exceptionally lightweight compared to modern accessory-heavy ARs. Magazine: Feeds from standard STANAG (AR-15) box magazines, originally shipped with straight-walled 20-round magazines. Key Visual & Design Features The SP1 is a true representation of the early Vietnam War-era M16 aesthetic, defined by several distinct vintage characteristics: Fixed Carry Handle Upper: The upper receiver features an integrated carry handle with an early A1-style rear peep sight that is only adjustable for windage."Slab-Side" Lower Receiver: Unlike modern AR-15 lowers, the SP1 lacks the raised protective "fence" around the magazine release button. No Forward Assist or Shell Deflector: Consistent with the earliest Eugene Stoner designs, original SP1s do not have a forward assist mechanism on the upper receiver or a built-in case deflector. Iconic Furniture: Equipped with a fixed polymer buttstock (featuring a hard rubber buttpad but no internal cleaning kit compartment), a straight A1 pistol grip without a middle finger groove, and the highly recognizable triangular polymer handguard. THIS WAS USED BY A DETROIT POLICE OFFICER DURING THE RIOTS.