The Stern Defense 015SD4INCHMOD4MLOK4INC 9mm complete upper receiver assembly brings a compact, Glock-magazine-compatible AR-15 pistol setup together in one well-matched package. Built around a 4 inch 4150 chrome-moly steel barrel with a melonite coating and a free float M-Lok handguard, this upper is designed for smooth operation and consistent performance. The engraved dust cover with "Get Stern" branding, Glock-cut BU9 bolt, and CH1 enhanced charging handle add practical upgrades and a distinctive look without unnecessary bulk.

This 9mm upper is ideal for range use, training, and pistol-caliber carbine style setups where reduced recoil and compact dimensions are preferred. The blast can muzzle device helps direct gases forward for a more comfortable shooting experience, while the full-length Picatinny rail offers ample space for optics. Paired with a compatible AR-15 pistol or Glock-magazine lower, it provides a straightforward path to a reliable pistol-caliber build that reflects Stern Defense’s focus on tight machining tolerances and thoughtful design.

Key Features:

• Manufacturer: Stern Defense
• Model: MOD4 9mm Luger 4" Complete Upper Receiver Glock
• Caliber: 9mm Luger
• Barrel Length: 4"
• Muzzle Device: Blast can muzzle device
• Handguard: Free float M-Lok handguard
• Bolt: BU9 Glock cut bolt
• Charging Handle: CH1 enhanced charging handle
• Upper Receiver Type: AR-15 complete upper receiver
• Thread Pitch: 1/2x36