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For those looking for an optic-ready platform, the SIGM400 SRP removes the front sight tower and
replaces it with an M1913 railed front gas block. This sight-ready platform allows the operator to mount any optic without worrying about the sight tower. The gas block accepts all iron sights designed to work on the Mil-Spec Picatinny rail.

Features: 
Direct impingement gas operating system with rotating locking bolt, 5.56 x 45 mm NATO Chrome-lined barrels with phosphate finish, Accepts most M16 type magazines, M16A2 Type flash hider.