SIG SAUER SIG556xi Modular, Multi-Caliber (5.56mm NATO, 300 AAC Blackout/300BLK, 7.62x39mm Russian) Gas Piston/Op-Rod Combat/Tactical Rifle/Carbine/SBR with Kalashnikov AK-47/AKM Configuration Capability! – DefenseReview.com (DR): An online tactical ...