KAK Industry K-SPEC Downward Venting 5.56 BCG with Dual Ejector Bolt

SKU: MO-425-0503-045

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KAK Industry K-SPEC Downward Venting 5.56 BCG with Dual Ejector C158 Bolt

The K-SPEC Enhanced AR15 BCG is a high-quality bolt carrier group designed for use with both 5.56 and 300 Blackout rifles. It features dual ejectors for reliable ejection of spent casings and a downward vent design to reduce gas blowback. The slotted carrier rails provide smooth and consistent operation. This BCG is built to withstand the rigors of extended use and deliver consistent performance.

Slotted Angled Carrier Rails

For enhanced functionality in adverse and rugged conditions such as sand, mud, dirt, and grime. These rail cuts are designed for debris disbursement, resulting in ultra-high functionality in the toughest conditions, including suppressor fouling and foreign contaminates. Strategically located angle cuts in the rails result in fouling and debris being moved into noncritical areas that are not in contact with the receiver and do not affect the function of the firearm. aka sand cutter

Downward Gas Vents

In an effort to reduce the amount of debris and gas vented toward the shooter’s face, the two standard gas relief ports have been relocated from the ejection port side of the K-SPEC carrier and placed underneath, in the magazine feed lip channels.  Two additional emergency relief ports have also been added to the bottom of the carrier to mitigate structural damage in the event of a case head separation.  Testing has shown that venting the gasses through the magazine well has no negative impact on the feeding or function of the magazine or ammunition, and any added heat is negligible.

Dual ejectors

The K-SPEC dual ejector system uses mil-spec ejectors and springs that require no proprietary parts.  Ejector holes are centered on the lugs to avoid any reduction in strength of the bolt.  The dual ejector system increases the ejection reliability and adds consistency to the ejection pattern. KAK Industry has been manufacturing dual ejector bolts for the AR10/LR308 platform for over a decade and has used that experience to create a durable and reliable dual ejector system for the AR15 platform.

KAK Industry takes pride in producing some of the finest Mil-Spec/ Enhanced AR15 bolt carrier groups available, made 100% in house at their MO facility using Doosan machining centers, Tsugami Swiss turning, and the latest in FANUC robotics combined into an automated cell giving us lights out production capability.  In house automated CMM Inspection processes ensure consistent quality. 


  • Designed to function reliably in the toughest conditions
  • Optimized for both Suppressed and Un-suppressed use, All uses – All Conditions
  • Dual Ejectors for enhanced reliability
  • Angled Carrier Rail Cuts for flawless function in adverse conditions and prolonged suppressed use
  • Downward Gas Ports to reduce gas blowback to shooter
  • Full Auto Profile
  • Magnetic Particle Inspected
  • High Pressure Tested
  • Permatex added between Gas Key and Carrier Mating Surface
  • Carrier- 8620 steel, outside rails, bolt runs, and gas bores ground to .0002 tolerances, nitride finish
  • Bolt- Carpenter 158 Bolt, outside diameters ground to .0002 tolerances, MPI test, nitride finish
  • Firing Pin- 8740 steel, Swiss turned, heat treated, precision ground, chrome plated
  • Cam Pin – 4140 steel, Swiss turned, heat treated, nitride finish
  • Extractor- 4140 steel, fully machined, Phosphate coated
  • Extractor pin- S7 tool steel, ground, heat treated
  • Ejector- S7 tool steel, ground, heat treated
  • Gas key – 4130 steel, heat treated, secured with T25 torx fasteners, torqued to spec, staked with  hydraulic staking machine
  • 11.5 oz


  • Brand: KAK Industry
  • Model: K-SPEC Downward Venting 5.56 BCG with Dual Ejector C158 Bolt
  • MPN: MO-425-0503-045
  • Material: Steel
  • Finish: Phosphate, nitride, chrome, and heat-treated
  • Color: Black
  • Weight: 11.5 oz
  • Caliber: 5.56/.300BLK
  • Fit: AR-15

Have Questions About this Product?

The AT3 Tactical store has a 90 day no-hassle return policy for products in good condition. You can view the full details of our return policy here.

If you encounter an issue or defect with a product after 90 days of your purchase, you can refer to the manufacturer for a warranty claim. Their policies are below.

KAK Industry Warranty Information

Our #1 priority is your 100% satisfaction. If any product you purchase from us ever fails to 100% meet or exceed your expectation, please contact us via telephone or EMAIL and we will attempt to resolve the situation to your satisfaction. If you need to return an item, returns are accepted subject to the following guidelines:

No Returns or Refunds are allowed after 30 days from Invoice Date.

  • Shipping costs both ways are non-refundable. Orders that were shipped to you at no charge with a “Free Shipping” offer will have the cost of the original shipping deducted from the refund amount.
  • New items that have been used may not be returned unless defective.
  • Returns must include all accessories as shipped. Refunds will be adjusted for returns missing accessories, factory boxes, etc. or may be returned to the customer at the customer’s expense, at our option. If you are keeping or have lost some of the pieces, please don’t return the item.
  • Items marked Closeout or Blem, as well as Special Orders may not be returned and their sale is final.
  • Items that are Custom contract manufactured may not be returned and their sale is final unless defective
  • Returned items may be subject to a restocking fee.
  • Any damaged shipments must be reported to the carrier immediately for proper claim handling.
  • All returns must be prepaid. Insurance on returns is at your option and at your expense and risk. COD returns will NOT be accepted and the package will be returned to you.

Contact Details

Address: 2241 Celsius Ave, Unit C, Oxnard, CA 93030
Telephone: 805-981-4734
Email: sales@kakindustry.com

Disclaimer: Manufacturer’s warranty is subject to change without prior notice.

Customer Reviews

Based on 4 reviews

I bought this for my Splenda Skunk build. My first experience shooting a gas gun suppressed and I was worried about getting gassed out.
I swapped the PSA has block out for a Superlative Arms and used a Radiant SP charging handle. Using a Thunderbeast Ultra 7 I had zero gas to the face. I probably could swap my Daniel Defense bolt in and see if that gives me more gas to the face. But not worth the ammo. Also shooting subsonic blackout not sure how much gas that'd put off. But either way it's a great BCG.
The dual extractors are super aggressive. With the gas tuned right the cases are banging the brass deflector hard. Leaving a mark.

Hi there, thank you for taking the time to leave a review for our KAK Industry K-SPEC Downward Venting 5.56 BCG with Dual Ejector Bolt. We're happy to hear that it worked well for your Splenda Skunk build and that you had a great experience shooting suppressed. It's always a relief to not have to worry about getting gassed out. We're glad our BCG was able to help with that. Thank you for choosing KAK Industry and we hope you continue to enjoy using our product. Happy shooting!

Jacob Helms
Does Something Different

Two things that justified the price for me. The extractor and the gas venting. When I add a modifier, it’s ready. Once I received it, the fit and finish was good.

Thank you for your review! We're glad to hear that the extractor and gas venting of our K-SPEC Downward Venting BCG stood out to you. We take pride in providing high-quality products that are ready to use with added modifiers. We appreciate your feedback on the fit and finish as well.

ronald Dye
Allows a lefty to actually shoot suppressed

Picked up 4 of these for my 4 sbr that I shoot suppressed. I cannot say how nice they are. No gas to the face. Even with non flow thru or RB cans.

We're so glad to hear that our K-SPEC Downward Venting BCG has allowed you to shoot suppressed with ease as a lefty. It's great to know that our product has met your expectations and provided a smooth shooting experience.

Lee Parke
Tamed the beast

I've tried alot of different gas mitigation devices but this is hands down the most effective at cutting down on gas to the face on my suppressed 10.5 5.56. Definitely recommend.

Thank you for taking the time to leave a review for our KAK Industry K-SPEC Downward Venting 5.56 BCG with Dual Ejector Bolt. We are glad to hear that our product has helped tame the beast of gas to the face on your suppressed 10.5 5.56. We appreciate your recommendation and are happy to know that our product is effective for you.