The Cobalt Kinetics CK-Pro Upper Receiver Group in 5.56 NATO with a 13.7-inch barrel and FDE finish (Cobalt Kinetics part no. CKPROURG556137BFDE) is a complete AR15-platform upper built for a mid-length 5.56 rifle or SBR build. Every CK-Pro URG in this configuration is hand-built by Cobalt Kinetics’ own gunsmith staff and test-fired for function before it ships, giving builders the same fit and reliability found in a complete CK-Pro rifle. The 13.7-inch barrel offers a balance of maneuverability and sight radius, and the flat dark earth Cerakote finish adds a durable, corrosion-resistant coating over the aluminum receiver. It’s machined to bolt onto any mil-spec AR15 lower receiver.

Key Specifications

• Chambered in 5.56 NATO, the standard AR15 chambering for widely available ammunition.
• Fitted with a 13.7-inch barrel, a popular mid-length option for balanced handling.
• Finished in flat dark earth (FDE) Cerakote for a durable, distinct look.
• Assembled and test-fired for function by Cobalt Kinetics’ gunsmith staff before shipping.
• Machined to mil-spec dimensions for compatibility with standard AR15 lower receivers.

Frequently Asked Questions

Is this a complete, built upper or a stripped receiver? This CK-Pro URG configuration is a fully assembled, test-fired upper.

Will this bolt onto a standard AR15 lower? Yes, it’s machined to mil-spec dimensions for compatibility with standard AR15 lower receivers.

Buy the Cobalt Kinetics CK-Pro Upper Receiver Group (5.56 NATO, 13.7-inch FDE)

Get a gunsmith-built, test-fired 13.7-inch 5.56 upper ready to drop onto your build. Order it from our Cobalt Kinetics lineup of AR15 uppers, shipped fast from our Lubbock, Texas gun shop.