Assertion: gun's barrel | /r/HasProperty | magpul mbus
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Source sentences:
text: It features a 5.5-inch barrel (with an option of a 6.5-inch barrel on the Gen II version), a folding stock, flip-up Midwest Industries back-up iron sights (BUIS) (MagPul MBUS on Gen II weapons), a full-length Picatinny rail for mounting various optics/scopes, and either two mode fire selector (single and full-auto) or a three mode fire selector (single, two-round burst and full-auto).