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36 of 60 Items
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    PSA 9MM SBA3 MOE EPT Pistol Lower Assembly Kit 1 PSA 9MM SBA3 MOE EPT Pistol Lower Assembly Kit 2 PSA 9MM SBA3 MOE EPT Pistol Lower Assembly Kit 3 PSA 9MM SBA3 MOE EPT Pistol Lower Assembly Kit 4 PSA 9MM SBA3 MOE EPT Pistol Lower Assembly Kit 5

    PSA 9MM SBA3 MOE EPT Pistol Lower Assembly Kit

    Here's the one-stop-shop for building a highly efficient and ergonomic lower for your next AR-9 pistol. This ensemble features parts from some of the best brands out there. First of all, you get the Magpul MOE trigger guard and pistol that will make...

    Was: $299.99
    Now: $189.99
  • Mil-Spec AR15 Lower Parts Kit (w/ Hammer and Trigger)

    Mil-Spec AR15 Lower Parts Kit (w/ Hammer and Trigger)

    This LPK offers the parts needed to finish your lower, and for a fraction of the cost of a "retail" bought assembly. This lower parts kit comes with all the internal parts needed to finish your lower, from the pivot pin to the trigger. With this kit...

    $39.99
  • Adjustable Carbine Stock & Buffer Tube Assembly Adjustable Carbine Stock & Buffer Tube Assembly Adjustable Carbine Stock & Buffer Tube Assembly Adjustable Carbine Stock & Buffer Tube Assembly

    Adjustable Carbine Stock & Buffer Tube Assembly

    This butt stock kit includes both an adjustable carbine stock and buffer tube assembly. The adjustable carbine stock is constructed from a durable polymer composite and is designed for quick adjustment. Additionally, this carbine butt stock offers three...

    $39.99
  • AR15 LPK - Missing Parts Kit

    AR15 LPK - Missing Parts Kit

    The AR15 Missing Parts Kit is perfect for any lost parts, replacement parts, or for your next custom build. What's Included? Buffer retainer (1) Bolt catch spring (2) Bolt catch detent (1) Selector detent (2) Disconnector spring (2) Buffer retainer...

    $9.99
  • Magpul® MOE® Carbine Stock & Buffer Tube Assembly Magpul® MOE® Carbine Stock & Buffer Tube Assembly 2 Magpul® MOE® Carbine Stock & Buffer Tube Assembly 3 Magpul® MOE® Carbine Stock & Buffer Tube Assembly 4 Magpul® MOE® Carbine Stock & Buffer Tube Assembly 5

    Magpul® MOE® Carbine Stock & Buffer Tube Assembly

    Get all the pieces you need to finish off the shoulder end of your AR in one handy little package. This bundle we've created gets you our buffer tube assembly, but that's not all. The bonus is that we've included a Magpul® MOE® Carbine Stock...

    $69.99
  • JMT Single Stage Drop-In 3.5-4 Ib Trigger - Saber JMT Single Stage Drop-In 3.5-4 Ib Trigger - Saber 2 JMT Single Stage Drop-In 3.5-4 Ib Trigger - Saber 3 JMT Single Stage Drop-In 3.5-4 Ib Trigger - Saber 4

    JMT Single Stage Drop-In 3.5-4 Ib Trigger - Saber

    If you're wanting a simple and effective upgrade to your AR to get you into that better-than-mil-spec territory with your trigger, then stop here and read this. You need to check out the Saber. It's JMT's Single Stage Drop-In 3.5-4 lb Trigger, and it'll...

    $99.95
  • LR-308/AR-10 Lower Parts Kit (w/ Hammer and Trigger)

    LR-308/AR-10 Lower Parts Kit (w/ Hammer and Trigger)

    We strive to provide the most accurate photographs of our product whenever possible. Due to availability limitations and supply chain constraints, slight variations of the trigger and hammer finsh (stainless or black) may occur.  If you're looking...

    $54.99
  • AR15 LPK - Basic Build Kit

    AR15 LPK - Basic Build Kit

    This AR15 Basic Lower Parts Kit includes all of the basic necessities needed for your own custom build. Most importantly what comes with this kit are the following, a bolt catch kit, magazine catch kit, takedown pin & detent & spring, pivot pin...

    $26.99
  • Magpul® MOE® AR-15 Build Kit Magpul® MOE® AR-15 Build Kit 2 Magpul® MOE® AR-15 Build Kit 3 Magpul® MOE® AR-15 Build Kit 4 Magpul® MOE® AR-15 Build Kit 5

    Magpul® MOE® AR-15 Lower Build Kit

    We don't want to say this is the kit to end all kits, because that would be too cliché. So we'll just tell you this is the kit to end the lower half of your AR build. If you got your hands on a stripped lower and you're ready to build, this kit...

    $134.99
  • AR15 Enhanced Carbine Buffer Kit by Aero Precision AR15 Enhanced Carbine Buffer Kit by Aero Precision AR15 Enhanced Carbine Buffer Kit by Aero Precision

    AR15 Enhanced Carbine Buffer Kit by Aero Precision

    You already know you need a buffer tube assembly on your AR-15. And usually it's nothing "special." You screw parts onto other parts, and it serves its purpose as part of your AR. You spend your hard-earned money on these parts, so it'd be great if...

    $70.99
  • Premium AR-15 Lower Parts Kit Premium AR-15 Lower Parts Kit 2 Premium AR-15 Lower Parts Kit 3 Premium AR-15 Lower Parts Kit 4

    Premium AR-15 Lower Parts Kit

    A lower parts kit is a key part to finishing your lower. It's one of the most important aspects of your AR-15 as far as quality is concerned. This lower parts kit offers all the parts needed to finish your stripped receiver. You'll also need an upper...

    $64.99
  • AR15 Ergonomic Pistol Grip by UTG®

    AR15 Ergonomic Pistol Grip by UTG®

    The UTG® AR15 Ergonomic Pistol Grip features a non-slip texture, palm swell, and thumb rest for maximum comfort and stability. The grip angle offers easy accessibility to the trigger along with increasing shooting accuracy for optimal performance. In...

    $10.99
  • LR-308/AR-10 Buffer Tube Assembly

    LR-308/AR-10 Buffer Tube Assembly

    If your in the market for buffer tube assembly kit, get yourself a kit that will guarantee longevity. Forged form 7075-T6 aluminum, the buffer tube is not only lightweight, but is extremely durable as well. It's also compatible with most aftermarket...

    $39.99
  • ARQD100 AR-15 QD Backplate by Sylvan Arms ARQD100 AR-15 QD Backplate by Sylvan Arms

    Sylvan Arms AR-15 QD Backplate

    By now, you're surely aware of the benefits of using a QD sling for your AR-15, and you've landed here because you're looking to upgrade. You have the sling, but where do you attach it, and what if you're left handed? If you prefer to keep your AR close...

    $19.99
  • 300 Blackout Pistol Buffer Tube Kit - 3 oz Buffer

    300 Blackout Pistol Buffer Tube Kit - 3 oz Buffer

    Finish your 300 BLK AR build with the right buffer. Getting supersonic and subsonic 300 Blackout loads to reliably cycle in your AR pistol requires dialing in your gas system and your buffer weight. This lightweight buffer kit includes a 3.0-ounce...

    $34.99
  • MOE® Mil-Spec Carbine Stock by Magpul® MOE® Mil-Spec Carbine Stock by Magpul® MOE® Mil-Spec Carbine Stock by Magpul® MOE® Mil-Spec Carbine Stock by Magpul®

    MOE® Mil-Spec Carbine Stock by Magpul®

    There's a reason Magpul is so great at what they do. Their parts are super rugged, they're as tough if not tougher than mil-spec stuff, and they usually weigh less too. The Magpul MOE® Mil-Spec Carbine Stock is no different. It's light, it's tough,...

    $37.99
  • AR9 Buffer Tube Assembly

    AR9 Buffer Tube Assembly

    Whether you're replacing an old part or getting started on a brand new build, we've got you covered with the AR9 buffer tube assembly kit. The buffer tube is forged from 7075-T6 aluminum which makes it very light and tough as hell. It's even compatible...

    $44.99
  • Sure Grip for AR-15/M-16 by Ergo Grip Sure Grip for AR-15/M-16 by Ergo Grip

    Sure Grip for AR-15/M-16 by Ergo Grip

    If you frequently use your AR for long durations, then comfort is key. You need to remove the potential for fatigue in your grip hand. With that in mind, Ergo Grip gives your their Sure Grip for AR-15/M-16. First, it's been contoured and shaped for max...

    $21.55
  • MOE® AR15/M4 Grip by Magpul

    MOE® AR15/M4 Grip by Magpul®

    Look, the AR-15 for how modular it is and how it can adapt to any situation, falls short in one key area: the grip is bad. Like real bad. There's no such thing as holding it right and being comfortable at the same time. The angle is horrible. The way an...

    $19.99
  • RA LE145 Tactical Drop-In Trigger RA LE145 Tactical Drop-In Trigger

    RA LE145 Tactical Drop-In Trigger

    If you're the operator, LEO, or hunter that needs one of the most upgraded and dependable triggers available, the LE145 Tactical Trigger from Rise Armament should be your top choice. This drop-in, single-stage trigger maintains a slightly more robust 4...

    $129.99
  • Gauntlet Arms AR-15 Minimalist Stock Gauntlet Arms AR-15 Minimalist Stock 2 Gauntlet Arms AR-15 Minimalist Stock 3

    Gauntlet Arms AR-15 Minimalist Stock

    Lightwest, padded, compatible with mil-spec buffer tubes. Bigger isn't always better. The Gauntlet Arms AR-15 stock provides that compact, "PDW" profile without sacrificing appropriate length of pull, comfort, nor cheek weld. It's a perfect balance of...

    $19.99
  • Magpul CTR® Carbine Stock – Mil-Spec Magpul CTR® Carbine Stock – Mil-Spec 2 Magpul CTR® Carbine Stock – Mil-Spec 3

    Magpul® CTR® Carbine Stock - Mil-Spec

    The Magpul CTR Carbine Stock has a light, anti-snag, A-framed design that protects the latch from accidentally releasing, causing the stock to collapse down. The detachable rubber butt-pad prevents slippage when pressed against the shoulder along with...

    $56.95
  • Aero Precision Enhanced Lower Parts Kit - M5, .308

    Aero Precision Enhanced Lower Parts Kit - M5, .308

    If you're planning an LR-308 build, a good lower parts kit is on your to-buy list. It'd also be nice if your lower parts kit came with a more comfortable grip than the standard A2 grip. Aero Precision makes a lower parts kit designed for their own M5, a ...

    $84.99
  • AR15 LPK Pin And Detent Kit by KAK

    AR15 LPK Pin And Detent Kit by KAK

    The KAK Industry AR15 Pin And Detent Lower Parts Kit was manufactured with top of the line materials for the best quality parts. This kit is great for replacement parts, a new build, or having spare parts. This kit comes with a pivot pin, takedown pin,...

    $19.99
  • UTG PRO Ambidextrous Grip by Leapers, Inc. - UTG UTG PRO Ambidextrous Grip by Leapers, Inc. - UTG UTG PRO Ambidextrous Grip by Leapers, Inc. - UTG UTG PRO Ambidextrous Grip by Leapers, Inc. - UTG

    UTG PRO Ambidextrous Grip by Leapers, Inc.

    You deserve more out of an AR-15's grip than the standard A2 grip. This is the UTG PRO Ambidextrous Grip by Leapers Inc. UTG. Aside from polymer construction, it's been given excellent ergonomics to reduce fatigue, and so you can get a purchase between...

    $14.97
  • Tactical Deluxe SureGrip for AR-15/M-16 by Ergo Grip

    Tactical Deluxe SureGrip for AR-15/M-16 by Ergo Grip

    If you're like us, you find the mil-spec A2 grip that came standard on your AR uncomfortable. Its hard plastic never really gets any more inviting to your hand, and its angle and texture don't stop your from getting fatigue, especially after periods of...

    $34.99
  • MOE-K2+® Grip – AR15/M4 by Magpul MOE-K2+® Grip – AR15/M4 by Magpul-2

    Magpul® MOE-K2+® Grip - AR15/M4

    The Magpul MOE-K2+ Grip has a strong rubber mold wrapping around the durable polymer body, preventing snags and damage, which allows this grip to outlast in rugged environments. The MOE-K2+ offers a sharp vertical grip angle, naturally placing the...

    $23.70
  • M5 .308 Standard Lower Parts Kit by Aero Precision

    M5 .308 Standard Lower Parts Kit by Aero Precision

    If you plan to start an LR-308 build, you're gonna need a good lower parts kit. Aero Precision makes a lower parts kit designed for their M5, which is their own proprietarily designed .308 rifle that can also work with your LR-308 build, provided yours...

    $74.99
36 of 60 Items

Finish or upgrade your stripped lower or fabricated 80% lower.

Finished your 80% lower? Grabbed a stripped receiver that you're ready to assemble? We've got you covered with all the AR lower assembly components you need -- or want to upgrade! Check out the mil-spec LPKs we have in stock. They work with all fabricated 80% units and every mil-spec "retail" lower on the market, including the various calibers you might own: 9mm, 5.56, .223, .308, 300 BLK and more.

Quality AR-15 Lower Parts, Triggers, and Kits

The stock AR trigger gets the job done, sure. But you can enjoy better shot placement and a more ergonomic grip with a few easy drop-in upgrades. We've partnered with Rise Armament, JMT, PSA, Hogue, and other top AR parts makers to offer up some of the best upgraded AR triggers and grips available for the AR platform. 

"How do I install my lower parts kit?"

Installing the lower parts kit in your stripped receiver or fabricated 80% lower is relatively easy. Some basic tools are required, which include:

Need help? Here's our detailed lower parts kit install guide!

"What parts do I need to finish my stripped lower?"

You'll need the following parts, which can all be found right on this page or by clicking the links below to filter products by type: 

Not sure what to buy? Here's our complete parts guide to building the AR-15.


DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At GunBuilders.com, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.

We are a national retailer of individual components and not all products depicted on this website are legal in every state. Shipping of various products found on this website are prohibited to some states (such as California, Connecticut, District of Columbia, Hawaii, New Jersey, New York, Rhode Island, and Washington). The information, pictures, text or products presented on this website are not a representation by us, and should not be understood by you, that any product or completed firearm is legal to assemble or own in your state of residence. We encourage each and every builder to perform their own research about the state and federal laws that apply to them. It is your responsibility to understand the law and we encourage you to consult with an attorney or your local ATF representative.