Sig Sauer SIG556 Classic 5.56 NATO Semi-Auto Rifle, 16 in, Long-Stroke Gas Piston, Folding Adjustable Stock, Diopter Sights
The SIG556 Classic delivers the Swiss-inspired configuration enthusiasts look for, built in the USA and based on the long-serving SG552/553 used by the Swiss military. This Classic variant pairs a 16-inch barrel and adjustable gas system with Swiss-style sights, a folding, length-of-pull adjustable stock, and ventilated polymer handguards. It also includes a full-length Picatinny top rail with T-markings and AR-15/M16 (STANAG) magazine compatibility.
Condition
Overall Condition: Good condition, showing some signs of prior use and handling.
Bore Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: The bore is clean with lands and grooves showing little wear. The BCG and chamber show minimal wear and usage.
What’s Included
- 1x 30-round aluminum AR-pattern (STANAG) magazine
- Bolt-on Picatinny accessory rail sections for the handguard (installed)
- Polymer Picatinny rail cover panels (installed on handguard)
Designed by Sig Sauer for the civilian market and rooted in the SG552/553 lineage, the SIG556 Classic brings Swiss-style features to a U.S.-assembled platform. Its long-stroke gas piston with a rotating bolt, paired with an adjustable gas regulator on the gas block, delivers a robust operating system tailored for 5.56 NATO.
The rifle uses an aluminum upper receiver with an integral T-marked Picatinny rail and an anodized finish, paired with a 7075-T6 forged-aluminum lower with an anodized finish. A full-length Picatinny top rail with T-markings runs the receiver, while the front sight on the gas block and a rotary diopter rear sight provide a precise, proven sighting setup.
The 16-inch barrel is threaded and fitted with an A2-style flash suppressor. Ventilated polymer handguards accept bolt-on rail sections, and this rifle includes installed accessory rail segments and rail cover panels for a clean, adaptable forend.
The Classic configuration features a polymer, skeletonized stock that folds to the side and offers an adjustable length of pull from 11.5 to 13.4 inches. The platform is AR-15/M16 (STANAG) magazine compatible and ships with one 30-round aluminum magazine. Receiver rollmarking indicates SIG Sauer Inc., Exeter, NH, USA.