Lower Parts Kit for AR-15
From complete kits to individual pieces, AT3 has the lower parts you need to build your ultimate AR-15.
We provide high-quality lower receiver parts kit, safety selector, and mag release. READ MORE
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AT3™
AT3™ FU-BAG™ AR-15 Lost Parts Kit – Springs, Detents, Replacement Components
Made an "Oops" with your New Build? You Detent-Launchin', Spring-Losin' Fool, you. We've all been there. Whether it's rolling the dice on that bargain bin LPK in your local...2 Options -
AT3™
AT3™ Castle Nut for AR-15 Buffer Tubes – 10 Colors Available
Secure Your AR15 Buffer Assembly with a Steel Castle Nut This steel castle nut is an essential piece of an AR15 buffer tube/stock assembly. With standard cuts for use with...10 Options -
AT3™
AT3™ Mil-Spec AR-15 Pivot Pin/Takedown Pin Detent Springs – 2 Pcs
Mil-Spec AR-15 Pivot Pin/Takedown Pin Detent Springs (2 Pieces) All AT3 Tactical lower receiver parts meet or exceed Mil-Spec. These parts are guaranteed to fit and function in your AR... -
AT3™
AT3™ Mil-Spec AR-15 Pivot Pin/Takedown Pin Detents – 2 or 10 Piece
Mil-Spec AR-15 Pivot Pin/Takedown Pin Detents - 2 Piece or 10 Piece All AT3 Tactical lower receiver parts meet or exceed Mil Spec. These parts are guaranteed to fit and...2 Options -
AT3™
AT3 Tactical 2 Stage Trigger Assembly for AR 15 – 4.5 lb Pull Weight
The Best Upgrade To Your AR-15 - Your Key To Faster And More Accurate Shooting! The AT3 2-Stage Trigger drops into your mil-spec lower for a huge upgrade to your... -
AT3™
AT3™ Pro-Builder™ AR-15 Lower Parts Kit – No Grip or Trigger Assembly
Perfect Lower Parts Kit for the Premium Builds This quality lower parts kit excludes the two most commonly upgraded components - the grip and the trigger assembly (fire control group).... -
AT3™
AT3 Tactical AR-15 Takedown and Pivot Pin Assembly
AR-15 Takedown and Pivot Pins with Springs and Detents If you're completing an AR-15 lower, you won't get far without a good set of takedown and pivot pins. These mil-spec...10 Options -
AT3™
AT3 Tactical AR-15 Safety Selector Assembly with Spring and Detent
AR-15 Safety Selector with Spring and Detent AT3's AR-15 Safety Selector Assembly comes with everything you need to install a new safety or replace your existing parts. This mil-spec style...10 Options -
AT3™
AT3 Tactical AR-15 Magazine Catch and Button Assembly
AR-15 Magazine Catch with Button and Spring Whether you're finishing a build or replacing stock parts, your AR-15 is going to need reliable magazine retention. This mil-spec assembly includes the...10 Options -
AT3™
AT3™ Enhanced Nickel Teflon AR-15 Trigger Assembly
A Simple Upgrade That Will Ultimately Improve The Accuracy And Performance Of Your AR The Enhanced Nickel Teflon trigger assembly features smooth, precision-machined engagement surfaces and Nickel Teflon coating that... -
Armaspec Anti-Walk Trigger and Hammer Pins
Perfect for Drop-In Triggers and Preserving Your Lower Armaspec Stainless Steel Anti-Walk pins are standard .154 sized pins for milspec lowers. These pins are designed to keep your hammer/trigger pins... -
AT3™
AT3™ Mil-Spec AR-15 Buffer Retainer Spring
Mil-Spec AR-15 Buffer Retainer Spring All AT3 Tactical lower receiver parts meet or exceed Mil Spec. These parts are guaranteed to fit and function in your AR and are perfect... -
AT3™
AT3™ Mil-Spec AR-15 Bolt Catch Spring
Mil-Spec AR-15 Bolt Catch Spring All AT3 Tactical lower receiver parts meet or exceed Mil Spec. These parts are guaranteed to fit and function in your AR and are perfect... -
AT3™
AT3™ Mil-Spec AR-15 Selector Detent
Mil-Spec AR-15 Selector Detent All AT3 Tactical lower receiver parts meet or exceed Mil Spec. These parts are guaranteed to fit and function in your AR and are perfect for... -
AT3™
AT3™ Mil-Spec AR-15 Selector Detent Spring
Mil-Spec AR-15 Selector Detent Spring All AT3 Tactical lower receiver parts meet or exceed Mil Spec. These parts are guaranteed to fit and function in your AR and are perfect... -
Anderson Manufacturing AR-15 Lower Parts Kit – Stainless Hammer & Trigger
Everything You Need To Complete Your Lower Receiver The Anderson Manufacturing AR-15 Lower Parts Kit is a complete lower components kit that includes everything you need to complete your lower... -
AT3™
AT3™ Mil-Spec AR-15 Bolt Catch Plunger
Mil-Spec AR-15 Bolt Catch Plunger All AT3 Tactical lower receiver parts meet or exceed Mil Spec. These parts are guaranteed to fit and function in your AR and are perfect... -
AT3™
AT3™ Ambidextrous AR15 Safety Selector – 10 Colors Available
A Quick Upgrade to Any AR-style Rifle The AT3 AR-15 Ambidextrous Safety Selector replaces your existing selector all allows for enhanced safety control for both right- and left-handed shooters. This...10 Options -
AT3™
AT3 Tactical AR-15 Bolt Catch Assembly with Spring, Plunger, and Roll Pin
Mil-Spec AR-15 Bolt Catch with Hardware The AT3 AR-15 Bolt Catch Assembly has everything you need to upgrade or replace an existing bolt catch on your AR-15 lower. You get...10 Options -
AT3™
AT3™ AR15 Mil-Spec Bolt Catch – 10 Colors Available
Mil-Spec AR-15 Bolt Catch The bolt catch is an essential part of what makes the AR15 such a great rifle. AT3's bolt catch is a great addition to your next...10 Options -
New
Battle Arms Development Enhanced Modular AR-15 Magazine Release
Battle Arms Development Extended Magazine Release The Battle Arms Development Enhanced Modular Magazine Release gives you a larger surface than mil-spec for faster mag changes. The EMMR uses a two-piece...4 Options -
Magpul Trigger Guard for AR 15 – MAG417
Curved Shape For Better Use Of Gloves in Cold Weather Operations The Magpul Trigger Guard is a drop-in replacement for the AR15/M4 weapons platform manufactured from enhanced polymer that is...4 Options -
AT3™
AT3™ Mil-Spec AR-15 Buffer Retainer
Mil-Spec AR-15 Buffer Retainer All AT3 Tactical lower receiver parts meet or exceed Mil Spec. These parts are guaranteed to fit and function in your AR and are perfect for... -
AT3™
AT3™ Mil-Spec AR-15 Pivot Pin – 10 Colors Available
Mil-Spec AR-15 Pivot Pin This heavy-duty Mil-Spec Pivot Pin securely locks into and holds the upper and lower receivers in place. It's made of 8620 Alloy steel and has a...10 Options
Other Lower Receiver Components for AR 15:
AR 15 Buffer Tube Parts (Receiver Extension)
AR-15 Triggers
ButtstocksLower Parts Kit for AR-15
Magazines & Parts
Pistol Grips
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