Stern Defense SD 4in Mod4 M-LOK 4in Barrel 9mm Black Complete Upper Receiver Black SDINBRLKK
$419.27 at Ammunition Depot · 5 stores
In stock
Best price
$460.45at OpticsPlanet
In stock Sale Lowest in 30 dayschecked Nov 13, 2026
Fits and works with
- Caliber
- 9mm · Shop matching ammo
- Bolt
- 9mm · Bolt carrier groups
- Barrel length
- 6" · Handguards
- Handguard length
- 6" · Barrels
Specifications
- Manufacturer
- Stern Defense
- Color
- Black
- Type
- Complete
- Platform
- AR-9
- Caliber
- 9mm
- Barrel length
- 6"
Where to buy
| Store | Price | Availability | Buy | Add to build |
|---|---|---|---|---|
| OpticsPlanet Best price | $460.45Salechecked Nov 13, 2026 | In stock | Buy at OpticsPlanet | |
| Ammunition Depot | $460.45checked Nov 13, 2026 | In stock | Buy at Ammunition Depot | |
| Battlehawk Armory | $390.33Salechecked Nov 13, 2026 | Check store | Buy at Battlehawk Armory | |
| GrabAGun | $470.45checked Nov 12, 2026 | Check store | Buy at GrabAGun | |
| Brownells 17.76% off · ends Nov 15 · exclusions apply | $470.45checked Nov 13, 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
Lowest in-stock price in the last 30 days: $460.45 at OpticsPlanet. Dashed line = out of stock. Tracking since Sep 28, 2026.
Show the prices as a table
| Store | Latest | Lowest | Highest |
|---|---|---|---|
| Ammunition Depot | $460.45 | $460.45 | $460.45 |
| Battlehawk Armory | $390.33 | $390.33 | $398.30 |
| Brownells | $470.45 | $470.45 | $470.45 |
| GrabAGun | $470.45 | $470.45 | $470.45 |
| OpticsPlanet | $460.45 | $460.45 | $460.45 |
Since Sep 28, 2026.
About this part
The SD Mod 5 9mm Upper Receiver 6in M-LOK Complete Black is an AR-9 complete upper receiver from Stern Defense. It's sold by 5 stores (2 in stock), from $390.33 to $470.45. The lowest in-stock price in the last 30 days was $460.45 at OpticsPlanet.
From the manufacturer
The Stern Defense SD Mod 5 9mm Upper Receivers are unique with handguards that extend beyond the end of the barrels. The 8.5" barreled upper has a 10" M-LOK free float handguard, and the 6" barreled upper has an 8" M-LOK free float handguard. To bring the muzzle out beyond the end of the handguard both uppers have SD HBC 9MM Blast Can installed. Both barrels have a 1-10 rate of twist, A 1/2-36 muzzle thread pitch, and a Melonite finish. 8.5" or 6" barrels M-LOK Free Float handguard Complete assembly with 9mm bolt and charging handle A 1/2-36 muzzle thread pitch SD BU9 9mm Bolt Included in the upper receiv Mfg: Stern Defense
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