K-SPEC Enhanced AR15 BCG, 5.56/ 300 Blackout , Dual Ejector, Down Vent, Slotted Carrier Rails

(14 reviews)
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The K-SPEC BCG combines multiple key features focused on increasing the reliability of your AR15 style firearm no matter if you are running suppressed or unsuppressed, and regardless of conditions.  The K-SPEC is a truly plug and play BCG that will accommodate whatever configuration your mission requires.

For those running suppressed, the K-SPEC requires no additional tuning or tweaking of the gas or recoil systems to run reliably.  Like all KAK BCGs, the K-SPEC is machined to the M16 full auto profile.

Reduced Peak DB Report

When used in conjunction with a silencer, the gas redirect produces a quieter report

See testing results here- Down Vent vs Side Vent DB reduction testing

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 sandcutter

Downward Gas Vents

In an effort to reduce the amount of debris and gas vented towards the shooters 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 nor 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.

  • 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
  • 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- 9310 steel, 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


Machined in house and assembled using only the finest steels and components. 

KAK Industry takes pride in producing some of the finest Mil-Spec/ Enhanced AR15 bolt carrier groups available, made 100% in house at our 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. 

Right Hand
Bolt Material:


  • 5
    Cycles great with suppressor

    Posted by Lance on February 12, 2024

    Swapped out BCG with this K-Spec Down Vent BCG after putting can on front of 556. Runs just fine. Noticeable decrease in puff to face from under bolt. Magazines and spent brass are dirtier. Whatever. I'm happy I did the conversion. Great product. Shipped quickly.

  • 5
    Ksepc bcg

    Posted by tom woods on January 10, 2024

    This thing works great on my suppressed ar pistol! It pushes the gas down instead of back in your face making it more enjoyable to shoot!

  • 5
    K-spec BCG

    Posted by jake on January 2, 2024

    works great, high quality bolt and is staked better than any I've seen in person from other companies. I only have a few hundred rounds with it so far but it runs well. I paired this with a radian raptor sd for future use with a can but haven't shot it with one yet so ill have to update the review when that time comes.

  • 5
    Suppressed 300 blackout

    Posted by Scott on December 12, 2023

    Love, this BCG works great on my 300 Blackout suppressed SBR

  • 5
    High Quality BCG with Great Features

    Posted by Shane Broussard on December 11, 2023

    So this is an excellent BCG even if it didn't have the extra features. Double ejectors, sand cuts, and downward venting are excellent. Extremely high quality design and machining. The downward venting does not make much difference in how dirty the gun is. And it does help with gas in the face when shooting suppressed. It is not a huge improvement, maybe 10 to 20% improvement. Likely won't purchase another downward venting BCG but will be purchasing another KAK BCG with the diamond cuts and the improved bolt.

  • 5
    K-SPEC enhanced AR-15 BCG

    Posted by john on October 30, 2023

    as yet untested, awaiting other parts. From strictly an engineering perspective the dual ejector feature is one I've been waiting a decade for. Has worked great in the 308 format.

  • 5
    KAK engineers cut a deal with aliens

    Posted by Ethan on October 16, 2023

    This bolt is literally alien technology! Build quantity and finish is absolutely top notch! This is most definitely a Gucci part that will take your build to the next level especially if you are planning on running a can. Absolutely cannot beat the quality for the price!

  • 5
    K-Spec BCG

    Posted by Zack on September 30, 2023

    Absolutely worth the money. It hasn't had any hiccups (other than my inability to ensure my gas system is tightened properly) doesn't throw gas in your face, doesn't rattle, and is supper consistent with where it throws brass. 6/5 stars especially with it being made right here in Missouri!

  • 3
    Bcg failure

    Posted by H&H Tactical on July 24, 2023

    Great concept but one ejector fell out after 30 rds. Company did however replace immediately.