This Complete Carbine A4 Upper from Rock River Arms (part no. 350L0328) is chambered in .350 Legend with a 16-inch chrome moly barrel at a 1-in-16 twist, paired with a 13-inch M-LOK free-float rail and an RRA Operator Brake threaded 1/2-36, plus a bolt carrier group, charging handle, and 10-round magazine.

Key Specifications

• Chambers .350 Legend.
• Barrel measures 16 inches, chrome moly, 1-in-16 twist.
• Includes a 13-inch M-LOK lightweight free-float rail.
• Threaded muzzle wears an RRA Operator Brake (1/2-36 thread).
• Sold as a complete upper with bolt carrier group and charging handle assembly.
• Includes a 10-round magazine.
• Part of RRA’s Tactical Carbine line.
• Sold as an upper assembly, so no FFL transfer is required to purchase it by itself.

Frequently Asked Questions

Does this include everything needed except the lower? Yes, it’s a complete upper with bolt carrier group, charging handle, and a 10-round magazine included, ready to pair with a compatible AR-15 lower.

Why 1/2-36 thread instead of a common 5/8×24? .350 Legend commonly uses a 1/2-36 thread pattern, which is why the included RRA Operator Brake is cut to that spec.

Buy the Rock River Arms A4 Complete Upper, .350 Legend, 16-Inch

Build a .350 Legend carbine with this Rock River Arms complete A4 upper, mag included. It ships fast from our Lubbock, Texas gun shop, and our AR-15 uppers selection has more complete AR-15 uppers.