AR-15 Parts Kits Demystified: A Beginner’s Guide

For those embarking on the journey of building their AR-15, parts kits provide a convenient and cost-effective solution. Demystify the world of AR 15 Part Kits with this beginner’s guide, offering insights into the components, types, and considerations for assembling your own AR-15.

1. Understanding Parts Kits

AR-15 parts kits typically come in two main types: lower parts kits (LPK) and upper parts kits (UPK). LPKs include components for the lower receiver, such as the trigger group, pistol grip, and safety selector. UPKs contain parts for the upper receiver, including the forward assist, ejection port cover, and other upper-specific components.

2. Types of Parts Kits

Lower Parts Kit (LPK):

  • Standard LPK: Basic components for the lower receiver.
  • Enhanced LPK: Includes upgraded trigger components for improved performance.
  • Stripped LPK: Excludes the fire control group, allowing for customization.

Upper Parts Kit (UPK):

  • Standard UPK: Common components for the upper receiver.
  • Stripped UPK: Excludes the barrel and bolt carrier group, providing flexibility for customization.
  • Build Kit: Includes a barrel, gas system, and other components needed for a complete upper assembly.

3. Components Included in LPKs

A typical Lower Parts Kit (LPK) includes essential components for the lower receiver:

  • Trigger assembly
  • Hammer
  • Trigger and hammer pins
  • Disconnector
  • Pistol grip with screw
  • Trigger guard and roll pin
  • Magazine catch assembly
  • Bolt catch assembly
  • Safety selector
  • Buffer retainer and spring
  • Takedown and pivot pins with detents and springs

4. Components Included in UPKs

An Upper Parts Kit (UPK) includes components for the upper receiver:

  • Forward assist assembly
  • Ejection port cover assembly
  • Charging handle
  • Gas tube
  • Gas block
  • Gas tube roll pin
  • Delta ring assembly

5. Considerations When Choosing Kits

Quality of Components:

  • Choose kits from reputable manufacturers to ensure quality components.

Trigger Options:

  • Consider an LPK with an upgraded trigger if you desire improved shooting performance.


  • Ensure compatibility between LPKs and UPKs to match your lower and upper receivers.


  • If customization is a priority, opt for stripped LPKs or UPKs, allowing you to choose specific components.

6. Building Your AR-15 with Kits

Building your AR-15 involves assembling the lower and upper receivers. Follow detailed guides, videos, or seek assistance from experienced builders to ensure a smooth and accurate assembly process.

Conclusion: Building Your Custom AR-15

AR-15 parts kits serve as a gateway for firearm enthusiasts to assemble their custom AR-15s. Whether you choose standard kits for simplicity or opt for enhanced components, understanding the basics of LPKs and UPKs empowers you to embark on a rewarding journey of customization and self-building.

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