Sale 15%

80% AR9/AR40 – Glock 9mm Mag w/LRBHO – Finger Groove Front – AR15 Based Lower Receiver – 7075 Raw



RAW – Finger Groove Front – 80% Dedicated GLOCK 9mm MAGAZINE with LRBHO AR15 LOWER RECEIVER – 7075-T6


Q – What does “Dedicated GLOCK 9mm MAGAZINE with LRBHO” mean?

A – Our lower is designed to accept Glock 9mm handgun magazines.  It includes an adjustable last round bolt hold open design (LRBHO) that works with all types of Glock Magazines and the LRBHO is adjustable. Also will function with .40 and .357 ammo.

Q – What is the difference between an AAO 80% lower and others?

A – Integrated Last Round Bolt Hold Open (LRBHO) – Our patent pending LRBHO is adjustable and it functions with all types of Glock Magazines

– Safe / Fire is laser etched into the AAO Lower.

– ALL AAO Lowers have a built in lower to upper adjustment feature that can be used to take up the slack/space between the upper/lower fitment (via an included allen head screw).

– You can quickly test your upper to lower fitment with the AAO Lower before you mill, this is due to a small pocket milled into the rear takedown pin area.

– High quality and best in class precision machining for a good price.  We are real gun guys and we fire what we make, so it has to be good.

Q – What material do you use?

A – All of our lowers are machined from: 7075-T6 Aluminum

Q – What LRPK (LPK) will work?

A – We recommend the AAO MFG LRPK, however any standard mil-spec LRPK will work.

Q – How does your last round bolt hold open(LRBHO) / empty bolt hold open work?

A – Our patent pending LRBHO is built into the Lower Receiver.  It is reliable, adjustable and works with all of the various magazine types on the market.

Q – Do I need to adjust my LRBHO?

A – Out of the box the LRBHO is adjusted to work with Glock magazines.  See our video on how to adjust for other magazines.

Q – What magazines work in the AAO Lower?

A -Glock, Magpul, Promag and most all others.

Q – What bolt carrier will work with this S&W M&P Mag lower?

A – An AR-9 Bolt Carrier that has been cut to clear a Glock Magazine.  On the S&W lower , we also recommend further clearance of one edge.

Q – Do I need to use a special buffer for my AR-9 build?

A – We recommend using a carbine buffer with a spacer.  The spacer limits the travel of the bolt carrier so it doesn’t break the bolt catch.

Q – Should I adjust my Ejector?

A – We recommend verifying that your bolt cycles without excessive rubbing on the ejector. We also recommend using loctite on the ejector bolts.

Q – What does RAW or “IN THE WHITE” mean?

A – Raw means “unfinished” or “in the white”, the unit has been fully deburred and is ready for you to finish.

Q – What does “Finger Groove Front” mean?

A – Finger Groove Front means that the outside front side of the magazine well area has been machined with Finger Grooves in it.  We also offer a Flat Front machining option for the front side of the magazine well.

Q  – What information do you need if I choose CA Compliance Engraving via the drop down menus?

A – Leave your information in the notes section of the checkout page.

  • CA Compliance list information as follows: Your Name, Your City, State, Multi Cal, Your Serial#
  • If ordering multiples lowers list your serial numbers as:  0001:0006 (serial number 0001 through 0006)

Q – Do you offer a bulk discount or other discounts?

A – Yes, purchase FIVE AAO Lowers and RECEIVE A 10% DISCOUNT on your lowers.

Q – What calibers can be built with this finished lower?

Glock 9mm, .40 and .357 (small frame)

Q – Is an FFL required to purchase this product?

A – NO, an FFL is NOT REQUIRED to purchase this product.

– Anyone can legally purchase a 80% Lower Receiver.  An 80% Lower Receiver DOES NOT have to be sold through or registered through a dealer with a FFL (Federal Firearms License).

Q – What JIG do you recommend to finish the AAO lower?

A – AAO Lowers are compatible with any JIG that will complete a standard Mil-Spec AR Lower.  If you are finishing an AAO 9mm Lower, the Ejector and LRBHO are removable so it can work with any standard Mil-Spec JIG.

Q – What are the operations that must be completed to make the 80% lower fully functional:

A – Machine the following using your JIG to finish our 80 percent AR15 Lower Receiver.  Our 80% Lower Receiver has a fully broached finished Mag Well.

  • fire control group
  • safety select hole
  • trigger opening
  • trigger pin holes
  • hammer pin holes
  • The AAO 80% Lower Receiver has been machined to match MIL-SPEC from a 7075 AR15 Lower Forging.

Q – What is a AR15 80% Lower Receiver?

A – 80% lower receivers are parts that have been partially completed.

– 80 percent or 80% is a generic term that means that everything is complete on the lower except for the fire control group, safety select, trigger opening, trigger pin holes & hammer pin holes.

– Utilizing a jig and the right techniques, any 80 percent lower can be quickly transformed into a highly accurate and functional firearm.

Q – Does a AR15 80% Lower Receiver require transfer or registration through an FFL? 

A – No. This is a do-it-yourself product.. You start with a 80% product and end up with a complete functional product after your finish the machining using your jig.

Q – Is it legal to do this?  May I lawfully make a firearm for my own personal use, provided it is not being made for resale?

A – This quote is taken directly from the ATF Website “Firearms may be lawfully made by persons who do not hold a manufacturer’s license under the GCA (Gun Control Act) provided they are not for sale or distribution and the maker is not prohibited from receiving or possessing firearms.”

Q – Can I build and then transfer a finished firearm to another individual? 

A – Yes you can, however you must mark the firearm in accordance with 27 CFR 472.92 (formally 178.92). You must follow all laws that are in place today. Do yourself a favor an protect yourself, don’t put a completed firearm in anyone’s hands unless you have gone through proper channels and background checks. Following the proper channels will protect us, our family, and our friends. For any firearm transfer it is your responsibility to understand the federal and local laws and how they apply.

Q – Is it legal to assemble a firearm from commercially available parts kits that can be purchased via the internet or via Firearms News?

A – This quote is taken directly from the ATF Web Site: “Firearms may be lawfully made by persons who do not hold a manufacturer’s license under the GCA provided they are not for sale or distribution and the maker is not prohibited from receiving or possessing firearms. However, a person is prohibited from assembling a non-sporting semiautomatic rifle or shotgun from 10 or more imported parts, as set forth in regulations in 27 C.F.R. 478.39”


Additional information

Weight 0.4535923696 kg
Dimensions 9 × 4 × 3 cm
Option - Bulk Order

Option - Safe / Fire Bullet Engraving

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Option - Serial Number / CA Engraving

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Extra Mag Well Engraving

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24 reviews for 80% AR9/AR40 – Glock 9mm Mag w/LRBHO – Finger Groove Front – AR15 Based Lower Receiver – 7075 Raw

  1. D_J

    This thing is owl snot slick! Very interesting LRBHO and perfect magwell. Threads are perfect, as are pin holes. Finger grooves give you a great surface if you’re building a pistol/SBR. Even though you’d have to have tiny fingers to fit them perfectly, they still work well.

  2. David Churchill

    The lower arrived in a timely fashion. I used my vision defense jig and milled the lower in about 2 to 3 hours. I mated the lower with mil spec upper. The fit was nice and tight. I plan on buying another lower soon. This lower is excellent quality. You won’t be disappointed.

  3. Rich Mallard

    First, it is a quality lower at a fair price compared to the rest of the market.
    Lrbho, took some time to get it to function.
    Finally had time test it more the just a couple of times while trying to get it to function.
    Used two Glock 15 round mags and one ETS 22 round mag.
    One Glock mag went 10 for 10 holding the bolt open, the second Glock mag went 8 for 10 and the ETS went 7 for 10.
    I consider that an -A and not bad after reading the forums on other lrbho set ups.

  4. Cliff M.

    I bought one of your glock mag lowers. The quality of the lower is awesome. The last round bolt hold open is awesome. I spent about 10min tweaking it using your video and it works flawlessly with my glock and ets magazines.

  5. Bill Simpson

    I own 4 other 9mm lowers. Yours is the best quality by far! Would recommend to others.

  6. Joey Hill

    Awesome product. Love the lrbho. Fast shipping.

  7. Robert Thompson

    The machine work and attention to detail are second to none on this lower. Lrbho functions great. Will be buying more.

  8. Tommy

    Fast shipping. Great quality. I will be purchasing more!

  9. Phillip

    Shipped the day after I ordered it. This is a bada__ lower. I will definitely order all my future lowers from this company.

  10. randy

    Got my lower in only three days. Great shipping time. Checked fit before finishing lower and after. Fit perfect to my upper. Product is top notch. Will be buying for them again.

  11. Carlos

    An excellent lower. I have a gen 1 80% arms easy lower jig. It worked perfectly in my standard lower jig after removing the ejector and LRBHO device. I haven’t finished the build yet but, I’m very pleased so far.

  12. Jamie L

    Quality product. The lrbho works perfect. Good price.

  13. Ashton B.

    You Guys build the best 9mm lowers on the market!

  14. jonathan k

    This is the best 9mm lower on the market. I have four pcc’s and have replaced all the original lowers i bought with yours. Fit is perfect, and the lrbho just works!

  15. Jagdogg

    Nice quality. Standard mill spec parts fit perfect. Thanks

  16. Jeff

    This lower is great! Nice and easy to machine. Fits well with my upper. Absolutely love the adjustment screw to take up slack between the upper and lower. Had a small issue with the LRBHO spring. It was sharp and hanging up on my magazine follower and tearing it up. I messaged AAO and they immediately sent out a new spring that seemed better. Worked like a charm without any adjustments!!! Great customer service!!!

  17. johnf

    Very good quality functions perfectly

  18. Don

    Its nice, i have a couple other glock mag lowers a NFA C9 i think (new frontier armonry model c9 i think) and it doesnt have a lrbho and a plastic mag catch, this has a
    Al mag catch andLRBHO seems like it will wokr well, im. finishing ATM and havnt tried it but everything seems nice.

  19. Craig Anderson

    Got it in, finished and coated. Love it. Holds open like it should. Got 300 rds threw it and no problems. Definitely recommend

  20. Heliman666

    Nice quailty part, good fit and finish… fast shipping .

  21. David L

    This is perfect for what I needed. Will be a nice addition to the collection.

  22. Guy from CO

    Quality in not lacking with AAO products. Fast shipping and good service.

  23. Willie

    Good quality product. Will purchase more.

  24. Alan Mummert

    Quality product, fast shipping and my Daytona Tactical jigs worked perfectly. I am very satisfied.

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