Colt AR-15 SP1 Pre-Ban (1979) 5.56 NATO with Later Colt 1/7 Gov't-Profile Barrel, Quad-Rail, Arm Brace, Gray Anodized
This 1979 Colt AR-15 SP1 is a pre-ban slabside example with the classic slick-side upper and gray anodized receivers, updated with practical, documented modifications. The factory pencil barrel was replaced with a later Colt 'C MP 5.56 NATO 1/7' government-profile barrel, and the furniture was modernized with a carbine-length Picatinny quad-rail and an adjustable polymer arm brace. It retains fixed carry-handle iron sights, a pinned A-frame front sight with bayonet lug, and original-style SP1 receiver markings.
Condition
Overall Condition: Very good condition, showing only light, superficial signs of prior handling or use.
Bore Overall Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Details: The rifle is in great shape with some scratches and blemishes present. The front pivot pin has been replaced with a non-retained option that removes with minimal resistance; the original SP1 used a two-piece screw-down design.
What’s Included
- 1x 20-round USGI-pattern aluminum straight-body magazine
- Carbine-length Picatinny quad-rail handguard (installed)
- UTG rail covers on handguard (installed)
- Adjustable polymer arm brace with hook-and-loop strap (installed)
- Open three-prong flash suppressor (installed)
Built on Colt's SP1 platform, this pre-1994 production rifle features hallmark early AR-15 traits: a slabside lower without a magazine-release fence and a slick-side fixed-carry-handle upper with no forward assist or brass deflector. The receivers are forged aluminum with a gray anodized finish, and the ejection port cover is present. Receiver markings include 'COLT AR-15 CAL. .223 MODEL SP1' on the left and 'COLT'S FIREARMS DIVISION / COLT INDUSTRIES / HARTFORD, CONN. U.S.A.' on the right with SAFE/FIRE selector.
The factory SP1 pencil barrel was replaced with a later Colt 'C MP 5.56 NATO 1/7' government-profile barrel. It is threaded and paired with an open three-prong flash suppressor. The 1:7 rifling twist is well-suited to modern 5.56mm NATO loads, and the bore condition is excellent with sharp rifling. A round A2-style delta ring secures the two-piece carbine-length quad-rail handguard.
Furniture and controls were updated with functional, modern components. The rifle wears a two-piece carbine-length Picatinny quad-rail with T- and B-numbered slots; the rail shows 'Made in USA' and the UTG shield logo, and UTG rail covers are installed. The carbine-length receiver extension is secured by a castle nut and a standard endplate (no QD socket), and an adjustable polymer arm brace with a hook-and-loop strap provides an approximately 11–14 inch length of pull; the visible QD sling cup is molded into the brace assembly.
Iron sights are retained in classic form. Up front is a pinned A-frame front sight base with a bayonet lug and sling swivel under the base. The rear sight is integral to the fixed carry handle. An A1-style checkered black polymer pistol grip completes the control layout. Capacity is 20+1 with the included magazine.
A notable small-parts detail: the original SP1 large-diameter two-piece screw pivot was replaced. The current front pivot pin is not retained to the lower and is easily removable with minimal resistance, aligning with the rifle's mixed vintage/modern configuration.