CMMG 16 Inch 22 Long Rifle Wasp Treated M4 Upper Receiver has a M4 profile barrel. The M4 profile barrel has a 1:16 inch twist ratio. The receiver is part of the phosphated .22 bolt group. Chambered in the 22 Long Rifle, save some money with the cheaper 22LR rounds! The receiver is 4140 Chrome-moly Steel. The railed gas block is the same height as the receiver.
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