Cobalt Blaster Builder

CK-Pro Fast Eddie 13.9″ 5.56×45


  • 13.95” Greenline Tactical/ Rosco Mfg. K9 series hybrid barrel.
    • 5.56X45mm (NATO)
    • 1/7 RH twist
    • Mid-length gas
    • 416R Stainless Steel barrel
    • Electro polished & Nitride coated
    • Continuous taper hybrid contour
    • Recessed target crown
  • Upper: 7075 T6 billet (Features Cobalt S.I.M.S. system).
  • Lower: 7075 T6 billet (feature integrated trigger guard).
  • Handguard: 13” 6061, 7-sided, M-Lok compatible.
  • Muzzle device: RCB-KM
  • Gas block: Cobalt (Non-Adj.), .750 Dia.
  • BCG: Cobalt, Full-Auto.
  • Charging handle: Radian Raptor LT.
  • Safety: Cobalt, Ambi.
  • Mag release: Ambi.
  • Trigger: Geissele 2-stage.
  • Buffer system: A5/ CK buffer system, anti-tilt buffer.
  • Grip: Reptilia CQG-L pistol grip.
  • Stock: Reptilia RECC-E stock (A5 compatible)
  • Warranty: LIFETIME

In-Depth Information

CK-Pro Fast Eddie 13.9″ 5.56×45 Details


A collaboration between Cobalt Kinetics X Greenline Tactical Consulting, The “Fast Eddie” is designed to meet and exceed the criteria for a practical rifle that can perform in the most austere (and unforgiving) environments while still being a refined tool. Critical factors taken into consideration during the design phase were; Accuracy, Operation, Recoil Mitigation, and Ambidextrous Adaptability. The end result is an elegant solution that shows what proper design and meticulous attention to detail can provide. *Final product may differ slightly from image shown. Please reference specs for accuracy of what you will receive when purchased.

Each CK-Pro comes with a LIFETIME WARRANTY.

*Exclusively Available at Firearms Depot

Pro Buffer System

This video illustrates the massive difference in recoil dampening comparing an average AR buffer system and the Cobalt Pro Buffer System.

Cobalt’s Pro Buffer System is among the most effective performance upgrades available for the AR today. The Pro Buffer System gives you an advantage by creating a smoother action and reducing recoil. We use low-friction, energy-absorbing polymers to make the buffer components and even the receiver extension is lined with a hard polymer film. All Cobalt Kinetics firearms include the Pro Buffer System out of the box.

Fit and Fitment

Every Cobalt Kinetics firearm is manufactured with extreme precision and accuracy. This results in near-perfect fit and fitment on every part of the gun. You will experience none of the typical AR rattling when manipulating a Cobalt.

Go ahead. Grab your AR by the grip and give it a shake. Hold the handguard along with the grip and twist the rifle. The loose fitment and structural integrity of a normal firearm are completely eliminated with a Cobalt.

Cobalt Dual Drop

This video demonstrates the functionality of the Cobalt Dual Drop System.

Cobalt’s patented Dual Drop mechanism is expanding the functionality of the classic AR-15 platform. Dual Drop improves weapon handling and reload speed faster. We put the system’s controls within reach of the thumb of the shooting hand. The Dual Drop adds a second forward assist control- mirrored on the left side of the upper receiver and mechanically connected to the right side assist and the bolt catch. Without adjusting your grip, you can press either forward assist and the bolt is released to reload the firearm.

Firearm Specifications

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The Cobalt Difference

Cutting Edge


Cobalt will never be satisfied with the status quo. We are always asking – Why? With our imagination, incredible engineers, and a desire to improve; we are constantly innovating an already amazing platform. We continue to explore how our innovative improvements can make you a faster and more accurate shooter. Innovation is at the core of who we are.

Military Grade


We torture test our rifles and pistols in the most extreme conditions, from the snow to the desert heat, they will function in any environment. The tight tolerances of the firearms protect the internal components from external elements. We Cerakote all our firearms to add to the durability. Multiple sources have reported that they have run our firearms in excess of the 50,000 rounds mark.

Match Grade


Our components are precisely engineered to the tightest tolerances. Our standards far exceed that of other manufacturers. We included match grade barrels and premium triggers in every firearm to enhance accuracy. Our Pro Buffer comes standard to reduce recoil allowing faster follow up shots. From the aggressive look and design to the quality of the components within, we are committed to assembling the finest firearms in the industry.



Every angle we cut, and every component we use, serves a function in our overall design that must be shot to be fully appreciated. At Cobalt Kinetics we source premium parts to compliment our high tolerances and precision engineering. Each component undergoes a strict quality control check before being installed into our firearms.