SIG Sauer SIG556 Classic 5.56 NATO Semi-Auto Rifle, 16" Threaded Barrel, Long-Stroke Gas Piston, Folding Adjustable Stock
The SIG Sauer SIG556 Classic blends the proven long-stroke gas piston system with the Classic 551-profile furniture. This USA-made rifle features a 16" threaded barrel with a 1:7 RH twist, a full-length receiver-top Picatinny rail with an integral flip-up emergency rear sight, and a two-position adjustable gas regulator. It accepts AR-15/M16 pattern magazines and carries Exeter, NH roll markings, tying it to the early U.S. production era.
Condition
Overall Condition: Very good condition, showing only light, superficial signs of prior handling or use.
Bore Overall Condition: Good - Clean, well-maintained, minor wear marks.
Bore Rifling: Good Rifling - Intact, well-defined lands and grooves.
Specific Condition Notes: This firearm is in solid shape, with scratches and blemishes present. The bore is clean and shiny.
What’s Included
- SIG Sauer SIG556 owner's manual
- Blue SIG Sauer factory hard case (labeled SIG556301)
- Rubber buttpad on Swiss-style folding stock (installed)
- 1x 30-round AR-15/STANAG pattern metal magazine
The SIG556 Classic uses a semi-automatic, long-stroke gas piston system with an adjustable two-position gas regulator at the gas block. This setup is designed for consistent cycling across conditions. The right-side charging handle follows the classic SIG 55x ergonomics and keeps reciprocating mass forward.
The rifle’s Classic configuration includes two-piece polymer 551-profile handguards and a Swiss-style side-folding stock with adjustable length of pull. A polymer buttpad is installed from the factory. The upper receiver is stamped steel and the lower is forged aluminum, creating a robust, balanced build.
The 16" barrel features a 1:7 RH twist and is threaded at the muzzle, fitted with an A2-style birdcage flash suppressor. This twist rate pairs well with a wide range of 5.56mm NATO projectiles.
Sighting equipment consists of a fixed front sight on the gas block and a flip-up emergency rear sight integral to the full-length Picatinny receiver rail. The rifle accepts AR-15/M16 pattern magazines and includes a manual safety for straightforward handling.
This example is roll-marked Exeter, NH and corresponds to MFG Part Number SIG556301. The factory case label is dated 16-Jun-2009 and matches the rifle’s serial on the label, documenting its configuration at the time of packaging in the U.S.