SD Mod 4 9mm Upper Receiver 16.1In M-LOK Complete Black

Name: SD Mod 4 9mm Upper Receiver 16.1In M-LOK Complete Black
Brand: Stern Defense
Availability: OutOfStock

Stern Defense · Upper Receiver

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Best price

$544.45at Brownells

Out of stock checked Oct 1, 2026

Buy at Brownells

Where to buy

Store	Price	Availability	Buy	Add to build
Brownells	$544.45checked Oct 1, 2026	Out of stock	Buy at Brownells

Prices and availability change often, so confirm on the store's site before you buy. We may earn a commission from these links.

Price history

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Dashed line = out of stock. Tracking since Sep 27, 2026.

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Store	Latest	Lowest	Highest
Brownells	$544.45	$544.45	$544.45

Since Sep 27, 2026.

About this part

The SD Mod 4 9mm Upper Receiver 16.1In M-LOK Complete Black is an AR-9 complete upper receiver from Stern Defense. One store lists it, Brownells at $544.45.

Fits and works with

Caliber: 9mm · Shop matching ammo
Bolt: 9mm · Bolt carrier groups
Barrel length: 16.1" · Handguards
Handguard length: 16.1" · Barrels

Specifications

Manufacturer: Stern Defense
Color: Black
Type: Complete
Platform: AR-9
Barrel length: 16.1"

From the manufacturer

A Complete Ready-to-Go Solution

The Stern Defense SD Mod 4 9mm Upper Receiver is a complete, ready to go, upper receiver solution for those looking to spend less time building and more time shooting.

The 16.1 inch, 1-10 twist, Melonited barrel, is free float in a 12in M-LOK handguard attached to a 7075-T6 forged aluminum receiver.

16.1in barrel
15in M-LOK Free Float handguard
Complete assembly with 9mm bolt and charging handle
½-36 muzzle thread pitch
SD BU9 9mm Bolt
Cartridge: 9mm Nato

Included in the upper receiver is charging handle and the Stern Defense 9mm Bolt which is compatible with both Glock and Colt SMG magazines, has a Melonite finish, and is works in conjunction with the Law Tactical Folding Adapter. The Stern Defense SD Mod 4 9mm Upper Receiver is made in the U.S.A.