Superior Arms S-15 5.56mm NATO Semi-Auto Rifle | Rare Boutique AR-15 with Free-Float Quad-Rail & Adjustable Trigger
Produced by the now-defunct boutique builder Superior Arms, this S-15 stands out for its 7075-T6 aluminum receivers, built-in trigger creep adjustment screw, and full-length free-float quad-rail handguard. With a low-profile gas block, Magpul furniture, and a threaded 16-inch barrel capped by a stainless multi-flute three-prong flash hider, the rifle offers features that collectors and shooters rarely find in a single package.
Condition
Overall Condition: Very good – shows only light, superficial signs of prior handling or use.
Bore Condition: Excellent – clean, mirror finish, no signs of wear.
Rifling Condition: Excellent – sharp lands and grooves.
Specific Condition Notes: External surfaces show just a few faint handling marks, with no finish loss. Both included magazines are equally clean.
What’s Included
- Superior Arms S-15 rifle
- 2 × 30-round Magpul PMAG polymer magazines
This rifle was built on a matched set of 7075-T6 upper and lower receivers finished in matte black anodizing. The lower houses Superior Arms’ signature adjustable creep screw, allowing the user to fine-tune trigger take-up without aftermarket parts.
A vent-hole free-float quad-rail handguard surrounds the 16-inch 5.56 NATO barrel and conceals a low-profile gas block for a clean sight picture and uninterrupted rail space. T-marked positions on the flat-top upper simplify repeatable accessory placement.
The barrel is threaded and topped with a stainless multi-flute three-prong flash hider, adding both function and a distinctive look. A stylised X-logo charging handle and rubber overmolded finger-groove pistol grip round out the controls.
Furniture includes a 6-position Magpul MOE-type collapsible stock with a 13-inch length of pull. Combined with the direct-impingement action, the rifle remains light, balanced, and compatible with standard AR-15 components.