Stern Defense MOD4 Upper 9mm 16.1in 15in M-LOK

The Stern Defense MOD4 is a complete 9mm AR-style upper built for reliable, pistol-caliber performance. It ships assembled with a 16.1″ Melonite-treated steel barrel and a 15″ M-LOK handguard, and uses a Glock-cut upper receiver that accepts Glock-cut lowers or Stern adapters. The package includes an SD BU9 Glock-cut bolt, an SD CH1 enhanced charging handle, and an SCB 9 compensator threaded to .5-36. Finished and assembled in the U.S., this upper is designed for range use, training, and competition-oriented pistol-caliber AR builds.

Key Specifications

• The caliber is 9mm.
• The barrel length is 16.1 inches.
• The barrel finish is Melonite.
• The barrel material is steel.
• The rate of twist is 1:10″.
• The muzzle is threaded to .5-36 and includes an SCB 9 compensator.
• The handguard is a 15-inch M-LOK modular rail.
• The upper is a Glock-cut receiver compatible with Glock-cut lowers or Stern adapters.
• Included are a complete assembled upper with SD BU9 bolt and SD CH1 charging handle.
• The receiver is 7075-T6 anodized aluminum and the product is Made in the USA.

Designed for shooters who value straightforward, high-quality components, the MOD4 upper provides a practical foundation for 9mm AR-style builds. Its combination of a Melonite-treated steel barrel, Glock-cut compatibility, and a long M-LOK rail makes it suitable for range sessions, training, and competition where reliable pistol-caliber performance and modularity matter.