The Sons Of Liberty Gun Works M4-L89 Upper Receiver Group is a purpose-built AR-15 upper designed for shooters who want dependable performance in a streamlined package. It pairs a 14.5" Liberty Fighting Barrel with a pinned and welded Plan B compatible flash hider to achieve a 16" overall length, all tucked under a 13.75" L89 free-float rail with 7-sided M-LOK slots and integral QD mounts.

This complete upper (less BCG and charging handle) is chambered in .223 Wylde / 5.56 NATO and uses a mid-length gas system for smooth cycling and controllable recoil. The forged upper receiver, chrome-lined 41V50 barrel, and nitrided gas system components are selected for long-term durability, making this upper well suited for range use, training, and general-purpose defensive setups. Sons Of Liberty Gun Works is known for carefully tuned, hard-use components that emphasize reliability and consistent accuracy.

Key Features:

• Manufacturer: Sons Of Liberty Gun Works
• Model: M4-L89 Upper Receiver Group
• Caliber: .223 Wylde / 5.56 NATO
• Barrel Length: 14.5" with pinned and welded Plan B flash hider (16" OAL)
• Rail Length: 13.75" L89 free-float M-LOK
• Gas System: Mid-length
• Upper Receiver: Forged AR-15
• Includes: Complete upper receiver group without BCG or charging handle