Building your own AR-15 can be a rewarding experience, offering a level of customization unavailable with pre-assembled rifles. A crucial component in this process is the complete lower parts kit (LPK). This guide will delve into the intricacies of LPKs, helping you understand what to look for, how to choose the right one, and what to consider during assembly.
What is a Complete Lower Parts Kit (LPK)?
A complete lower parts kit contains all the essential components needed to complete the lower receiver of an AR-15 rifle. This excludes the lower receiver itself, which is often purchased separately due to legal requirements and serial number registration. The LPK forms the heart of the firearm's functionality, controlling the firing mechanism and interaction with the upper receiver.
Components Included in a Typical LPK:
A standard LPK typically includes the following parts:
- Hammer: Strikes the firing pin, igniting the primer.
- Hammer Pin: Securely holds the hammer in place.
- Disconnector: Prevents automatic fire by interrupting the hammer's movement.
- Trigger: Initiates the firing sequence when pressed.
- Trigger Pin: Holds the trigger and disconnector in place.
- Bolt Catch: Locks the bolt to the rear after the last round is fired.
- Bolt Catch Roll Pin: Secures the bolt catch.
- Safety Selector: Engages or disengages the firearm's safety mechanism.
- Safety Selector Detent: A small spring and pin that keep the safety selector in place.
- Safety Selector Spring: Works with the detent to ensure proper safety selector function.
- Buttstock Retaining Pin: Secures the buttstock to the lower receiver.
- Magazine Catch: Releases the magazine from the lower receiver.
- Magazine Catch Button: The button you press to release the magazine.
- Magazine Catch Roll Pin: Secures the magazine catch.
Choosing the Right Complete Lower Parts Kit:
The market offers a vast array of LPKs, ranging in price and quality. Consider these factors when making your selection:
1. Material:
Most LPKs are made from steel, but some components might utilize aluminum or other materials. Steel is generally preferred for its durability and strength. Look for components made from high-quality steel to ensure longevity and reliability.
2. Finish:
Various finishes are available, including phosphate, hardcoat anodizing, and nickel boron. Phosphate is a common and cost-effective option, offering decent corrosion resistance. Nickel boron is known for its extremely smooth finish and reduced friction.
3. Manufacturer Reputation:
Research the manufacturer's reputation before purchasing. Choose a reputable brand known for producing high-quality, reliable parts. Reading online reviews can help you gauge the quality and performance of different LPKs.
4. Price:
While budget-friendly options exist, avoid extremely cheap LPKs, as these may compromise quality and reliability. A moderate investment in a reputable brand is generally worthwhile.
Assembly and Installation:
Assembling an AR-15 lower receiver requires careful attention to detail. Numerous online resources, including videos and step-by-step guides, are available to assist you. It's crucial to follow these instructions precisely to ensure proper functionality and safety. If you are unsure about any aspect of the assembly process, consider seeking assistance from an experienced gunsmith.
Beyond the Basics: Enhanced LPKs
While a standard LPK provides the essential functions, you can find enhanced LPKs featuring upgraded components. These might include:
- Drop-in trigger groups: Offer improved trigger pull weight and feel.
- Enhanced safety selectors: Provide a more positive engagement and improved tactile feedback.
- Ambidextrous controls: Allow for operation from either side of the firearm.
These enhancements can significantly improve the shooting experience and overall performance of your AR-15.
Conclusion:
Selecting and assembling a complete lower parts kit is a key step in building your AR-15. By carefully considering the factors outlined above and following proper assembly instructions, you can ensure a functional and reliable firearm. Remember to always prioritize safety and seek professional assistance if needed. This guide provides a solid foundation for your understanding of LPKs; further research and due diligence will greatly assist you in completing your AR-15 build.
