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.
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- Lower Receiver Parts - AT3 Tactical (49)
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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 -
Armaspec SFT45/90 Ambi AR 15 Safety Selector – ARM113
Armaspec 45 and 90 Degree Ambi Safety The Armaspec SFT45/90 allows you to modify your AR-15 safety exactly how you like it. This AR-15 safety upgrade features a double-sided steel...6 Options -
CMMG .308 Lower Receiver Parts Kit
All the Parts You Need to Get Started on Your Next Mk3 Build Combine this kit with a buttstock kit to complete your lower group. Compatible with CMMG Mk3 Lowers... -
AT3™
AT3™ Mil-Spec AR-15 Pivot Pin/Takedown Pin Detent Springs – Set of 2
AT3™ Mil-Spec AR-15 Pivot Pin/Takedown Pin Detent Springs - Set of Two All AT3 Tactical lower receiver parts meet or exceed Mil Spec. These parts are guaranteed to fit and... -
AT3™
AT3™ MOTHERFU-BAG™ – The BIG AR-15 Lost Parts Kit – Springs, Detents, Wear Parts,...
Launch a detent? Snap a spring? Don't get mad, just fix it with this AR-15 Lost Parts Kit! Alright, so y'all seem to like the FU-BAG. Like a lot. Which... -
AT3™
AT3™ Mil-Spec AR-15 Pivot Pin/Takedown Pin Detents – 2 or 10 Piece Set
AT3™ Mil-Spec AR-15 Pivot Pin/Takedown Pin Detents - 2 or 10 Piece Set All AT3 Tactical lower receiver parts meet or exceed Mil Spec. These parts are guaranteed to fit...2 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 -
NEW
Magpul MOE Enhanced AR-15 Trigger Guard
Transform Flat Mil-Spec Dimensions into Tactile Ergonomic Perfection The MOE Enhanced trigger guard overhaul ushers forgiving glove integration and positive control to the overlooked lower receiver component. Ditch the awkward...3 Options3 Options3 Options -
AT3™RECOMMENDED
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)....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 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™ 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™ 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 buffer assembly and... -
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 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 safety assembly and are... -
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 -
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™RECOMMENDED
AT3™ AR-15 Enhanced Billet Trigger Guard Assembly
AT3 Billet Trigger Guard - Perfect for Winter and Gloves This billet aluminum trigger guard works with all mil-spec lower receivers, and makes additional room for manipulating the trigger. The...9 Options -
Strike Industries AR-15 SHIFT Takedown and Pivot Pins
Strike Industries AR-15 SHIFT Takedown and Pivot Pins Effortlessly maintain your AR15 with Strike Industries' Shift Pins. Featuring an extended grip surface and Quick Detach mechanisms, these pins simplify disassembly...3 Options3 Options3 Options -
Strike Industries Fang AR-15 Trigger Guard
Rugged and Refined Aluminum AR-15 Trigger Guards Elevate your AR's style and performance with the Strike Industries Fang Aluminum Trigger Guard. This eye-catching billet aluminum upgrade goes far beyond basic...4 Options4 Options4 Options -
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 lower receiver and... -
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. This US made pin is made of 8620 Alloy...10 Options -
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 mag catch assembly...
Other Lower Receiver Components for AR 15:
AR 15 Buffer Tube Parts (Receiver Extension)
AR-15 Triggers
Buttstocks
Lower Parts Kit for AR-15
Magazines & Parts
Pistol Grips
AR-15 Trigger Guards