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Stern Defense SD Mod4 M-Lok 9mm Complete Upper Receiver 015-SD4INCHMOD4MLOK4INCHBARREL9MM-KK Caliber: 9mm Luger, Barrel Length: 4 in, 12% Off After Instant Savings w/ Free S&H

Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
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Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
2 of 5 images
Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
3 of 5 images
Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
4 of 5 images
Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK
5 of 5 images
Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK

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Questions & Answers
What buffer weight is recommended, with and without a silencer? Manufacturer Answer

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

by STERN DEFENSE, Manufacturer, March 26, 2025
What is the inside diameter of the hand guard? I would want to add an NFA suppressor. Manufacturer Answer

1.43 inches in diameter

by STERN DEFENSE, Manufacturer, November 27, 2024
View All Q&A You Have a Question? Ask!
Customer Reviews
Helpful Positive Review It's cool for an all-in-one 9 mm upper by Peter, July 10, 2020
I assumed that it was a dedicated 9 mm upper that it would not have a forward assist it seems as though they used some surplus uppers 4 rifle cartridge and just built pistol caliber uppers still cool just not dedicated more like a Frankenstein
3/10 found this helpful
Helpful Positive Review great to shoot by jimbo, February 12, 2021
Great to have and fun to shoot. Small light weight and versatile. Using if for multiple applications either hunting coyotes or training. I’m in love shooting it but since ammo is rare and hard to come by I haven’t had much play time lately.
2/2 found this helpful
Most Recent Reviews 9mm Complete Upper by Sp33dy, Verified Owner, April 2, 2025
Great upper receiver couldn’t pass on a deal when it went on sale. Watched videos and reviews how well Stern Defense 9mm holds up and I was very impressed how sustainable the barrel is. After receiving my upper, I test it at the range and I was at a...
Read More...
Read All 3 Reviews

This Labor Day Holiday Save 10% On All Stern Defense Products!

See details.
$41.92 Instant Savings Applied
Get a 10% savings instantly when purchasing this product before September 6th, 2025! Sales price already reflects these instant savings!
Caliber: 9mm Luger Barrel Length: 4 inBarrel Twist Rate: 1-10 Finish: Matte Color: Black Additional Features: Threaded .5-36 Condition: New

Code: 3JS-URC-SDURCSDMML9-SDINBRLKK

MPN: 015-SD4INCHMOD4MLOK4INCHBARREL9MM-KK

UPC: 850001176200

$41.92 Instant Savings Applied
List: $429.27Save 12%
$377.35

Product Info for Stern Defense SD Mod4 M-Lok 9mm Complete Upper Receiver

Stern Defense 4 inch M-LOK rail(Barrel nut, bolts etc.)image

Stern Defense 4 inch 9mm barrel.

SD MBC 9MM Blast Can.

Stern Defense assembled upper receiver with dust cover and forward assist.

Stern Defense SD BU9 Glock cut bolt.

SD CH1 enhanced charging handle.

Will come assembled.

Information:

Handguard.

The free float M-LOK handguard from Stern Defense offers excellent ergonomics while remaining lightweight and strong. This handguard is M-LOK compatible to accept your favorite attachments. Features a secure clamp on mounting system that ensures that the handguard remains in place even under heavy abuse, sustained full auto fire, and shooting prone from a bi-pod. Machined from 6061 aircraft grade aluminum and hard-coat anodized for longevity and durability. These handguards also feature quick disconnect swivel holes.

Also Included, Barrel Nut and Bolts.

Specifications for Stern Defense SD Mod4 M-Lok 9mm Complete Upper Receiver:

Manufacturer: Stern Defense
Caliber: 9mm Luger
Barrel Length: 4 in
Barrel Twist Rate: 1-10
Finish: Matte
Color: Black
Fabric/Material: Melonite
Additional Features: Threaded .5-36
Condition: New
Magazine Included: No

Features of Stern Defense SD Mod4 M-Lok 9mm Complete Upper Receiver

  • Barrel length is measured in overall length from breech to muzzle.
  • Caliber: 9mm.
  • Length: 4 Inches.
  • Threaded .5-36.
  • 1:10 TWIST.
  • 4150 Chrome-moly steel.
  • Melonite coating.

Package Contents:

  • Stern Defense SD Mod4 M-Lok 9mm Complete Upper Receiver

Stern Defense SD Mod4 M-Lok 9mm Complete Upper Receiver Orderable Models

List of Orderable Models

Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK , MPN: 015-SD4INCHMOD4MLOK4INCHBARREL9MM-KK , UPC: 850001176200 , Code: 3JS-URC-SDURCSDMML9-SDINBRLKK

Stern Defense SD Mod4 M-Lok 9mm Complete Upper Receiver Unavailable & Discontinued Models

List of Unorderable Models

USED, Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK , MPN: 015-SD4INCHMOD4MLOK4INCHBARREL9MM-KK-EDE , Code: 3JS-URC-SDURCSDMML9-SDINBRLKK-EDEMO-RE-C
USED Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm, Black Complete Upper Receiver, Black, SDINBRLKK, EDEMO1, Condition Fair, Other , MPN: 015-SD4INCHMOD4MLOK4INCHBARREL9MM-KK-EDE , Code: 3JS-URC-SDURCSDMML9-SDINBRLKK-EDEMO-OT-D
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