Orders ship within 24 hours or by the next business day!

phone: 888-310-0284
36 of 60 Items
  • 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...

    $38.99
  • 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
  • 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...

    $63.99
  • 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
  • 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
  • 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 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
  • 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...

    $46.74
  • 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
  • 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...

    $29.99
  • 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
  • AR15 Enhanced Lower Parts Kit by Aero Precision

    AR15 Enhanced Lower Parts Kit by Aero Precision

    For your next AR-15 build, you should start your lower receiver with a quality lower parts kit, so you don't just end up replacing it later. With that in mind, Aero Precision gives you their AR-15 Enhanced Lower Parts Kit to start your build off in a...

    $79.99
  • ARH300 - Folding Stock Adapter by Sylvan Arms ARH300 - Folding Stock Adapter by Sylvan Arms ARH300 - Folding Stock Adapter by Sylvan Arms ARH300 - Folding Stock Adapter by Sylvan Arms ARH300 - Folding Stock Adapter by Sylvan Arms

    Sylvan Arms Folding Stock Adapter (ARH300)

    Set up your AR-15 to make it more easily stowable when you carry with you to the range. No more carrying around huge bulky rifle bags and cases. Make your rifle short enough to fit into something smaller. Shorten it for travel with the AR-15 and AR-9...

    $149.99
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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...

    $18.99
  • Drop-In Trigger - RA-140 Super Sporting Drop-In Trigger - RA-140 Super Sporting

    Drop-In Trigger - RA-140 Super Sporting

    "Man, I wish I had a kickass trigger for my AR, that didn't cost half what the entire rifle was worth." Ever thought this? Well stop wishing, and check out the RA-140 Super Sporting Trigger Assembly by Rise Armament. Use this step-by-step guide to...

    $129.99
  • SBA3 MOE Pistol Lower Build Kit

    SBA3 MOE Pistol Lower Build Kit

    Looking for a convenient way to complete your pistol-sized AR? Complete your AR-15 pistol build the right way with the SBA3 MOE Pistol Lower Build Kit! It features the quality SBA3 pistol brace by SB Tactical and an upgraded lower parts kit. This SBA3...

    $219.99
  • 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
  • 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
  • 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
  • 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
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.