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CMMG describes that this kit is designed to function with their MkG series lowers. Will this kit work in a stock upper/lower? — 3 Answers

by Canidae, from UT, United States Asked on December 19, 2018

Name CMMG, Inc 9mm Barrel and Bolt Carrier Group (BCG) Kit (3.6)
$499.95 $469.99 Save $29.96
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A
Answered by Ethan C., Gear Expert, from IL, United States, on November 03, 2019

Yes, you can use a milspec upper and lower receiver with this kit.

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A
Answered by TK, member, from HI, United States, on August 13, 2021

This Cmmg RDB bolt & barrel kit will work with most Mil-Spec uppers & lowers, you will also need the Cmmg 9arc magazines. This Radial-Delayed Blowback system is different from your normal Blowback system, actually 10X better! and you don’t need any dedicated 9mm upper & lower your regular ar15 mil-spec will work just fine. Keep in mind this is a three part system RDB barrel, bcg & mags.

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Answered by TK, member, from HI, United States, on August 03, 2021

Cmmg recommends you use a mil-spec upper with a 5.56/223 ejection size port & not a 9mm upper with the smaller size ejection sized port.

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Last updated 2026-02-01 UTC.