SIG Sauer P556 – 5.56 NATO Pistol, Quad Rail, SB Tactical Brace – Swiss-Inspired Gas Piston System

This SIG Sauer P556 pistol delivers classic SIG 550-series reliability in a compact, modernized package. Built around SIG’s proven short-stroke gas-piston operating system, the P556 offers exceptional reliability, reduced fouling, and smooth cycling compared to direct-impingement platforms.

The rifle-inspired steel receiver gives the gun a rugged, battle-proven feel, and the factory quad-rail handguard provides ample space for lights, grips, and other accessories. The pistol also includes an SB Tactical adjustable arm brace, making it compact, maneuverable, and well-suited for CQB environments and range use.

This example features a 5.56 NATO chamber, A2-style flash hider, full-length top rail for optics, and SIG’s distinctive Swiss-pattern controls. The markings on the receiver identify it as “P556, 5.56 NATO, SIG Sauer, Exeter, NH” with the serial TP 000522, confirming it as a USA-built variant based on the iconic SG 550 family.

Specifications