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Q&A for Stern Defense SD Mod4 M-Lok 9mm Complete Upper Receiver — 15 Questions & 15 Answers

Name Stern Defense SD Mod4 M-Lok 9mm Complete Upper Receiver (4.7)
$429.27 $419.27 Save $10.00
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Q
Anonymous, member, from GA, United States, asked on January 01, 2025

What buffer weight is recommended, with and without a silencer?

Manufacturer Answer
A
Answered by STERN DEFENSE, Manufacturer from MO, United States, on March 26, 2025

Without Suppressor 5.4 ounces and a standard carbine spring. With Suppressor 7.5 ounces and a standard carbine spring.

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Q
Brady, guest, from UT, United States, asked on September 07, 2024

What is the inside diameter of the hand guard? I would want to add an NFA suppressor.

Manufacturer Answer
A
Answered by STERN DEFENSE, Manufacturer from MO, United States, on November 27, 2024

1.43 inches in diameter

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Q
Yup, member, from TX, United States, asked on July 08, 2024

Is the barrel threaded so you can add your own comp or possibly a can?

Manufacturer Answer
A
Answered by STERN DEFENSE, Manufacturer from MO, United States, on November 27, 2024

It is threaded at 1/2-36 we do sell and adapter to 1/2 -28. (1/2-36 to 1/2-28 thread adapter)

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Q
Brad H, member, from LA, United States, asked on May 22, 2022

Is the BCG included a ramped BCG or not? I don’t see if it is or isn’t anywhere

Manufacturer Answer
A
Answered by STERN DEFENSE, Manufacturer from MO, United States, on June 02, 2022

Yes, it is a ramped bolt.

2 of 2 found the following answer helpful.
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Q
g52879, member, from OH, United States, asked on December 05, 2021

is the bcg that comes with this upper cut to allow for auto sear/binary trigger use?

Expert Answer
A
Answered by Hunter, Gear Expert, from OH, United States, on January 25, 2022

The manufacturer doesn't specify if the Stern Defense SD Mod4 M-Lok 9mm Complete Upper Receiver bolt can be used with binary triggers. I suggest you contact the manufacturer or email us at techsales@opticsplanet.com for more information.

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Q
Mike, member, from IN, United States, asked on November 30, 2021

Is there enough room on the bottom to mount a hand stop?

Expert Answer
A
Answered by Ethan, Gear Expert, from IL, United States, on January 13, 2022

Yes. There are many small handstop options available that cant mount to the MLOK rail on this upper. Below is a link to a handstop that I recommend.

https://www.opticsplanet.com/fortis-manufacturing-reversible-shift-handstop.html

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Q
Julio, guest, from NM, United States, asked on October 19, 2021

Will this fit a P80 G150 lower?

Expert Answer
A
Answered by Hunter, Gear Expert, from OH, United States, on January 25, 2022

The Stern Defense SD Mod4 M-Lok 9mm Complete Upper Receiver will fit a Standard AR15 Lower. So if the P80 G150 has Mil Spec dimensions then it will fit.

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Q
Joe, member, from VA, United States, asked on January 27, 2021

Will this upper work with a Spikes tactical 9mm lower for glock mags ST9G.

Expert Answer
A
Answered by Ryan Tarczynski, Gear Expert, from IL, United States, on May 04, 2021

This is a standard Mil-Spec AR15 upper receiver, so you will be dropping it into a standard Mil-Spec AR15 Lower.

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Q
Macky, member, from NV, United States, asked on October 08, 2020

Will this work with Endomag 9mm Pmag?

A
Answered by Brandon, member, from UT, United States, on December 22, 2020

This is a standard Mil-Spec upper receiver, so you will be dropping it into a standard Mil-Spec Lower. The EndoMag should function correctly, as the included BCG functions with Colt SMG and Glock magazines, just like the EndoMag is designed to do. Stern Defense also offers several variants of AR15 magazine adapters for different pistol magazines, as well.
https://www.opticsplanet.com/stern-defense-mag-ad9-ar-15-glock-9mm-40-magazine-conversion-adapter.html

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Q
Brad Leable, member, from IL, United States, asked on October 06, 2020

will this work with a cmmg lower

A
Answered by Brandon, member, from UT, United States, on December 22, 2020

This is a standard Mil-Spec AR15 upper receiver, so you will be dropping it into a standard Mil-Spec AR15 Lower.

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