AR-9 Modular 9mm BCG (Glock & Colt Compatible)

4.50 out of 5 based on 4 customer ratings
(4 customer reviews)


  • Manufacturer: New Frontier Armory
  • Model: AR-9 Modular 9mm BCG (Glock & Colt Compatible)
  • Caliber: 9mm
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  • Manufacturer: New Frontier Armory
  • Model: AR-9 Modular 9mm BCG (Glock & Colt Compatible)
  • Caliber: 9mm
  • Weight: 16.7 oz

AR9 Modular Bolt 02

AR-9 Modular 9mm BCG (Glock & Colt Compatible)

  • High quality US made steel with black oxide finish
  • Innovative two piece modular design for easy caliber and carrier weight changes and easy cleaning/maintenance
  • Uses standard AR-15 extractor and spring for increased reliability and more consistent ejection
  • Unique design provides an additional 2 oz of mass over most standard 9mm bolts enhancing operation
  • Ramped carrier to work with both 9mm and standard AR hammers
  • Precision milled for use with both Glock style or traditional Colt style AR-9 lower receivers
  • M-16 cut for use in transferable full auto MG’s, dealer post sample MG’s or other legal machine guns (ALL BATFE RULES APPLY)

**NOTE:  Many Aftermarket drop in triggers use modified hammers which may not reset properly, or hit the firing pin square on the carrier which could cause firing pins to bind and snap.  We recommend using only MILSPEC hammers with any 9mm, .40, or .45 blow back bolt carrier groups.


When re-assembling this BCG after cleaning — PLEASE be sure the firing pin spring is FULLY seated on the firing pin head before re-installing.  Not following these instructions can cause unnecessary wear and premature breakage and will not be covered under warranty.


The New Frontier Armory AR-9 Modular 9mm Bolt Carrier Group is proudly MADE IN THE USA by hard working American men and women.

Additional information

Weight 1.1 lbs
Dimensions 7.25 x 1.5 x 1 in

4 reviews for AR-9 Modular 9mm BCG (Glock & Colt Compatible)

  1. 4 out of 5

    (verified owner)

    So I just received my New Force Armory AR-9 Modular 9mm BCG (Glock & Colt Compatible) today for use in my New Force Armory AR-9 Glock Small Frame Lower that I purchased from Joe Bob Outfitters. When I installed the BCG in my rifle with a CMT Machining Upper, the would not close all the way. Try as I might the upper would not completely close due to something not fitting with the BCG. I put the BCG in a rifle using another company’s Glock Small Frame lower and the same situation. I called NFA and sent an email telling them I was considering sending it back. I took a bunch of photos because I wanted to be prepared to explain to NFA what the issue was should they start questioning me and just started fiddling with it when I discovered what the issue was.

    The large ejector (the white steel or aluminum hook sticking out of the top of the lower) is too wide across the top to allow the bolt to sit low enough for the upper and lower to close all the way. I was finally able to persuade the rifle to close up and started working the bolt by hand. I noticed rub marks on the top of the ejector closest to the left side of the lower as looking down from above. After several minutes of hand cycling the bolt, it start working smoothly. I took the upper and lower apart and I can now get them to close up with little effort. I continued working the bolt and it has worn a small piece of material of off the top of the ejector, about a 1/1000th of an inch. I took some fine grit sand paper to the ejector and smoothed it out. I test fired 50 rounds of 115 grain 9mm FMJ through it and the BCG worked flawlessly. Now I am just waiting for the release of the AR-9 C-9 LRBHO upper so I can complete this build.

    So the point of this long story is to tell you that the BCG has tighter tolerances than the ejector has and if you have problems fitting your upper to your lower, very gently sand and round off the top of the large metal ejector on the left side as looking down on the lower from above and the bolt should seat fine and the upper close up as it should. Once I got this taken care of the BCG ran fine. I like the modular design and while I don’t see me making any caliber changes, for $30 – $100 less than the nearest BCG manufacturing competitor I could not be happier. Hopefully NFA will read this review and make the ejector less thick.

  2. 5 out of 5

    The problem with the ejector apparently has been fixed. My AR9 lower and Modular 9mm BCG fit together perfect! Was smooth as butter!

  3. 5 out of 5

    (verified owner)

    500+ Rounds using New Frontier Billet Lower, regular cheapy mil-spec forged upper, New Frontier BCG, New Frontier 9mm Buffer Tube Cap Thing, New Frontier 9mm Barrel, SGM 32 Round Magazine. Not a single hiccup. Very happy. Now if the New Frontier Billet Uppers come back in stock, Ill be made in the shade.

  4. 4 out of 5

    (verified owner)

    purchased this bolt and the NFA 80% 9MM Lower receiver. Good price and fast shipping. Thank you NFA. All was good however with the bolt in a CMMG upper receiver the bolt wouldn’t fit in the buffer tube. I removed all suspect parts, hammer, ejector, buffer retainer, buffer, and spring and the bolt still wouldn’t enter the buffer tube. Removed the buffer tube and noticed that it had some ridges. After filing and sanding the ridges off the opening I could get the bolt to go into the buffer tube. However it still drug on the top of the bolt. I then used a 1″ scope ring lapping rod and some 220 lapping compound until the rod would move freely in the buffer tube. Still not enough, the bolt still drug enough that it would stick in the buffer tube. I then did what I didn’t want to do. I took it to the lath and removed 10 thousands off the back 2-3/8″ of the bolt, and it now cycles like it should. Don’t know if it had to do with the CMMG and NFA pairing or the bolt and or buffer tube were just out of spec. I guess I could have tried a different buffer tube but didn’t have a spare other than one all ready installed on other builds. they all seamed to measure the same.

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