2 barrel with receiver and gas system – SIG SAUER SIG556 User Manual
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2.1.2 Barrel With Receiver And Gas System
The barrel is mechanically mated to the receiver. The flash suppressor is screwed onto the muzzle end of the barrel
which features a 0.5 x 28 TPI thread pattern. The gas block, which is fixed on the barrel, contains the gas port, locates
the gas system (gas tube and operating rod), accepts the front sight and also serves as support for the hand guards. The
receiver guides the bolt and bolt carrier, and houses the locking system. An accessory mounting rail is fixed to the upper
part of the receiver, providing an attachment point for sighting systems and other accessories.
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