U.S. Special Operations Command is planning to buy a small number of conversion kits from Swiss gun maker Sig Sauer to turn existing M4A1 carbines into new MCX Rattler personnel defense weapons, or PDWs. This purchase is in response to the command’s nearly year-old requirement for a tiny assault rifle able to fire both .300 Blackout and 5.56x45mm rounds, which we at The War Zone were first to report.
The U.S. Army, which is managing the contract on behalf of Special Operations Command (SOCOM), announced the plan on FedBizOpps, the U.S. government’s central contracting website, on Feb. 1, 2018. The proposed deal, which the service expects to finalize by the end of March 2018, will include 10 complete “MCX PDW” upper receiver groups in .300 Blackout and equal number of 5.56x45mm barrels. The notice and its attached documentation never specifically mention the Rattler trade name, but the caliber, 5.5-inch barrel length, and mention of a thin, side-folding “skeleton” buttstock are a perfect match for the design that Sig Sauer debuted at the annual SHOT Show trade show in Las Vegas, Nevada in January 2018.