Sons of Liberty Gun Works M4-EXO3 13.7" 5.56 NATO Upper Receiver Group – Mil-Spec AR-15

The SOLGW M4-EXO3 13.7" upper receiver group delivers a compact, pinned-and-welded configuration in 5.56 NATO, optimized for close-to-mid-range engagements. This complete upper fits mil-spec AR-15 lower receivers and features a 13.7" barrel with a permanently attached muzzle device to meet the 16" legal minimum, eliminating NFA registration requirements while maintaining a reduced overall length. The EXO3 rail system provides M-LOK attachment points and a low-profile design that balances weight savings with rigidity.

Built with a forged 7075-T6 aluminum upper receiver and a chrome-moly-vanadium barrel with a carbine-length gas system, this upper is finished in a durable black anodized coating. The assembly includes a bolt carrier group and charging handle, ready to install on your lower receiver. No additional compliance work required—install, zero, and run.

• Caliber: 5.56 NATO
• Type: Complete Upper Receiver Group
• Compatible Lower: Mil-Spec AR-15
• Barrel Length: 13.7" (pinned and welded to 16")
• Material: Forged 7075-T6 aluminum receiver, chrome-moly-vanadium barrel
• Finish: Black anodized
• Includes: Bolt carrier group, charging handle, EXO3 M-LOK handguard
• Installation: Drop-in fit for mil-spec AR-15 lowers