The Colt AR-15 A2 Government Model, designated by Colt as the R6550, is a semi-automatic rifle chambered in 5.56x45mm NATO. The R6550 was produced by Colt from 1986 to 1990, using the GS serial number prefix throughout its production run. The rifle uses a direct gas impingement operating system with a rotating bolt locked by seven lugs. The upper receiver is forged aluminum with an integral carry handle housing a rear aperture sight adjustable for windage and elevation. The lower receiver is forged aluminum, marked "AR-15 A2 Government Model". The front sight is an adjustable post mounted on the front sight base, which also serves as the gas block.

This example bears a GS serial number prefix, identifying it as a Colt R6550. The rifle is fitted with a 20 inch barrel with a 1:7 inch twist rate, threaded muzzle, and A2 birdcage flash hider. Furniture consists of a fixed A2 buttstock with a trapdoor storage compartment, two piece A2 round handguards, and an A2 pistol grip. No magazine, original box, or accessories included.

Specifications

• Manufacturer: Colt
• Model: AR-15 A2 Government Model (6550)
• Caliber: 5.56x45mm NATO
• Action: Semi-automatic, direct gas impingement, rotating bolt
• Barrel: 20 inches, threaded muzzle
• Twist Rate: 1:7 inches
• Muzzle Device: A2 birdcage flash hider
• Receiver: Forged aluminum, upper and lower
• Finish: Black anodized
• Stock: Fixed A2 buttstock
• Handguards: A2 round, two piece
• Grip: A2 pistol grip
• Sights: Adjustable front sight post, rear aperture sight integral to carry handle, adjustable for windage and elevation
• Safety: Selector lever, left side of lower receiver
• Magazine: None included