Gun Parts Directory: The Builder’s Master Hub

A firearm is a system of precision components working in harmony. A successful build is a matter of sourcing the right parts. This is your master directory for every component, spring, and pin needed to build, repair, or upgrade your firearm. We have organized our entire inventory of high-quality, vetted hardware into a logical, easy-to-navigate hub. Stop searching and start building.

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 How to Find Your Parts: A Builder’s Guide

We’ve structured our inventory based on how a firearm is actually built. Use this directory to navigate by system and platform to find exactly what you need.

• By Firearm Platform: Start here if you know you are building an AR-15 or a Glock-style pistol.
• By Firearm System: Use this if you are looking for a specific component group, like a trigger assembly or a slide.
• By Build Method: Find parts specific to 80% builds or 3D printing projects.

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Browse All Parts by Firearm System

(This section is the core of the page. It uses large, clickable visual cards or text blocks for clear navigation to the more specific sub-categories.)

 The Upper: Slides & Upper Receivers

This is the operational half of the firearm, containing the barrel and bolt. For pistols, this is the slide assembly. For rifles, it’s the complete upper receiver.

• [Link] Complete Pistol Slides →
• [Link] Complete AR-15 Uppers →
• [Link] Barrels, Bolts & Internals →
  [Main Link Button] Shop All Uppers & Slides →

 The Lower: Frames & Lower Receivers

The serialized or “80%” foundation of your build. This system houses the fire control group and serves as the mounting point for all other components.

• [Link] AR-15 80% Lowers →
• [Link] Pistol 80% Frames →
• [Link] 3D Print Hardware & Rails →
  [Main Link Button] Shop All Frames & Lowers →

The Internals: Lower Parts Kits (LPKs)

The heart of your firearm’s function. The LPK contains the trigger, hammer, safety selector, and all the small pins and springs that make the firearm operate.

• [Link] AR-15 Lower Parts Kits →
• [Link] Pistol Lower Parts Kits →
• [Link] Upgraded Trigger Groups →
  [Main Link Button] Shop All Lower Parts Kits →

The Furniture: Stocks, Grips & Accessories

The user interface of your firearm. This category includes stocks, buffer tubes, grips, and braces that determine the ergonomics and handling of your build.

• [Link] Stocks & Braces →
• [Grip] Pistol & Rifle Grips →
• [Link] Buffer Tube Assemblies →
  [Main Link Button] Shop All Furniture →

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FAQ: Understanding Firearm Parts

Q1: What is a Lower Parts Kit (LPK)?

A1: A Lower Parts Kit (LPK) is a package containing all the small internal components needed to complete a stripped lower receiver. This includes the trigger assembly, hammer, safety selector, pins, and springs required for the firearm to function.

Q2: What is the difference between an upper and a lower receiver?

A2: The lower receiver is the main body of the firearm that houses the fire control group and is legally considered the “firearm” itself. The upper receiver contains the barrel and bolt carrier group. The two halves join together to form a complete rifle.

Q3: Are all AR-15 parts interchangeable?

A3: Most AR-15 parts that are “mil-spec” (built to military specifications) are interchangeable. This standardization is a key feature of the platform. However, parts from different platforms, like an AR-10, are not compatible. For a deep dive into compatibility, The Firearm Blog offers excellent technical articles.

Q4: Is it legal to buy gun parts online?

A4: Yes, in the United States, it is federally legal to buy unregulated gun parts such as barrels, slides, upper receivers, and lower parts kits online and have them shipped to your home. Only the finished frame or lower receiver requires shipment to a licensed dealer (FFL).

Q5: What are the first parts I should upgrade?

A5: For the most noticeable performance improvement, the first parts to upgrade are the trigger (for a better feel and improved accuracy), the optics (for faster target acquisition), and the barrel (for enhanced mechanical precision).