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Q&A for CMMG, Inc Upper Receiver Parts Assembly AR15-MK9/M4 — 18 Questions & 19 Answers

Name CMMG, Inc Upper Receiver Parts Assembly AR15-MK9/M4
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Q
Lefteris, guest, from VA, United States, asked on July 29, 2020

Will this fit a 223 wylde lower?

Expert Answer
A
Answered by Tom B, Gear Expert, from IL, United States, on October 18, 2021

Yes it will.

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Q
Joel, guest, from FL, United States, asked on November 11, 2022

Does this upper has lrbho features?,would it fit in a C-5 lower mew frontier armory?

Expert Answer
A
Answered by Ethan, Gear Expert, from IL, United States, on February 27, 2023

Unfortunately, the CMMG, Inc Upper Receiver Parts Assembly AR15-MK9/M4 has been discontinued by CMMG. You would need a 9mm upper receiver that is compatible with MP5 magazines such as the Jacob Grey Firearms Billet AR-9 Stripped Upper Receiver, found by using the link below:
https://www.opticsplanet.com/jacob-grey-custom-billet-jg-9-stripped-upper-receiver.html?_iv_code=4M6-UPR-BLS1-JG9URA

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Q
big woockie, member, from KS, United States, asked on July 05, 2022

would this work with a ks47 lower

Expert Answer
A
Answered by Hunter, Gear Expert, from OH, United States, on July 18, 2022

The CMMG, Inc Upper Receiver Parts Assembly AR15-MK9/M4 will not work on the KS47 Lower. That lower is designed to accept AK magazines and will not work with this upper.

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Q
David, member, from SC, United States, asked on June 30, 2022

Is this mill spec?

Expert Answer
A
Answered by Hunter, Gear Expert, from OH, United States, on July 14, 2022

The CMMG, Inc Upper Receiver Parts Assembly has some Mil-Spec dimensions. However, it is not a true Mil-Spec upper receiver.

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Q
Chance Clayton, member, from WY, United States, asked on June 19, 2022

What is the piece that is covering the dust cover?

Expert Answer
A
Answered by Hunter, Gear Expert, from OH, United States, on March 27, 2023

The piece on the CMMG, Inc Upper Receiver Parts Assembly AR15-MK9/M4 by the ejection port is the gas deflector.

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Q
Steve, member, from WI, United States, asked on November 21, 2021

This is fully compatible with CMMG's radial delayed blow back system? I assume so but why not ask. Thanks!

Expert Answer
A
Answered by Ethan, Gear Expert, from IL, United States, on June 20, 2022

Yes, this CMMG, Inc Upper Receiver Parts Assembly AR15-MK9/M4 is compatible with the CMMG Radial Delayed Blowback System and components.

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Q
Myself, member, from MO, United States, asked on October 25, 2021

Will this work with any ar15 mil spec lower?

Expert Answer
A
Answered by Patrick, Gear Expert, from IL, United States, on November 11, 2021

Yes, this will be compatible with mil-spec lower.

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Q
Leland Johnston, member, from TX, United States, asked on October 25, 2021

Is this a complete upper receiver?

Expert Answer
A
Answered by Patrick, Gear Expert, from IL, United States, on November 11, 2021

This is an assembled upper receiver not a complete upper.

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Q
Joe, member, from IL, United States, asked on September 02, 2021

It doesn’t state, but I would assume that it should work with a 45acp build, right?

Expert Answer
A
Answered by Tom B, Gear Expert, from IL, United States, on October 18, 2021

The ejection port might not be opened up enough. Per the manufacturer: The Mk4 platform accepts standard AR15-style magazines, and is the most versatile of the CMMG platforms, especially with the .22 LR, 5.7x28mm (Conversion), and 9mm conversions.

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Q
Ben, member, from NJ, United States, asked on December 19, 2020

Will this fit PSA PX9 lower?

Expert Answer
A
Answered by Tom B, Gear Expert, from IL, United States, on October 18, 2021

Because of the custom nature of your PSA lower, they state: Must be used with a Palmetto State Armory Hybrid 9mm Upper.

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