Geissele Automatics SD-556 Super Duty Mod 1 5.56 NATO, DDC, 16 in (13.9 in P&W) AR-15 with Ambi Controls & Free-Float M-LOK
This Geissele SD-556 Super Duty Mod 1 stands out with its factory 13.9-inch barrel capped by a permanently pinned and welded multi-prong muzzle device, delivering a listed 16-inch barrel length. Finished in Geissele DDC with Type III hardcoat anodizing across the receivers, buffer tube, and handguard, it features ambidextrous controls, a free-float M-LOK handguard, and a B5 Systems Bravo adjustable stock. The factory box label matches the rifle’s configuration: "SUPER DUTY MOD 1, 13.9", P&W, DDC."
Condition
Overall Condition: As-new condition with no signs of prior handling beyond what’s typical from inspection (see photos).
Bore Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: This rifle is in fantastic shape with minimal wear or use evident beyond factory testing.
What’s Included
- Factory Geissele cardboard box with serialized label for SD-556 Super Duty Mod 1 (13.9" P&W, DDC)
- 1x 30-round polymer STANAG-pattern detachable magazine
- M-LOK QD sling cup installed on handguard
The Super Duty Mod 1 configuration centers on a factory 13.9-inch barrel paired with a permanently pinned and welded multi-prong muzzle device, resulting in a listed 16-inch barrel length. The barrel is threaded from the factory, and the P&W work is factory-done for a secure, ready-to-use setup.
The free-float M-LOK handguard provides a full-length 12 o’clock Picatinny top rail, Geissele center-tab indexing, and two clamp bolts for solid retention. This layout supports accessory placement while keeping the barrel free-floated for consistent performance.
Controls are fully ambidextrous, including the safety selector, magazine release, and charging handle. An enlarged, textured "maritime" bolt catch aids manipulation. The rifle uses a flat-faced trigger, a Geissele polymer pistol grip, and a B5 Systems Bravo adjustable stock to round out a practical, user-focused interface.
The upper is forged-style with a forward assist, ejection-port cover, and a T-marked top rail. Type III hardcoat anodizing in Geissele’s DDC color is applied across the receivers, buffer tube, and handguard, delivering a unified finish. The factory box label matches the rifle’s serial and configuration details as "SUPER DUTY MOD 1, 13.9", P&W, DDC."