Building an AR-15 from the ground up can be an exciting and rewarding experience, especially for those who enjoy customizing their firearms. The lower receiver is a crucial part of this platform, housing many essential components that enable the rifle to function. This beginner’s guide will break down the key components of an AR-15 lower, helping you to understand what each part does and how they come together to create a reliable firearm.
The Lower Receiver
The lower receiver is the serialized part of the 4 inch arp AR-15 that is legally considered the firearm itself. This component serves as the foundation for the other parts and is where many critical components are assembled.
Material Choices
- Aluminum: Most AR-15 lowers are made from either 6061 or 7075 aluminum. The latter, 7075-T6, is stronger and more durable, making it ideal for high-stress applications.
- Polymer: Some lowers are constructed from high-quality polymer, which can be lighter and more affordable, though they may not always provide the same durability as aluminum lowers.
When selecting a lower receiver, consider the material that best fits your needs in terms of weight, cost, and durability.
Fire Control Group (FCG)
The fire control group includes critical components such as the trigger, hammer, and disconnect. It is responsible for the firing mechanism of the AR-15.
Main Components
- Trigger: This component is pulled by the shooter to fire the firearm. Triggers can vary in pull weight, feel, and design.
- Hammer: When the trigger is pulled, the hammer strikes the firing pin, igniting the cartridge.
- Disconnector: This part ensures that the hammer doesn’t fall again until the trigger is released, preventing unintended multiple shots.
Upgrading Your FCG
Many builders choose to upgrade their fire control groups to improve performance. Aftermarket triggers can offer a smoother pull and quicker reset, enhancing overall shooting experience.
Pistol Grip
The pistol grip serves as the primary interface between the shooter and the rifle, affecting comfort and control.
Ergonomics and Texture
- Ergonomics: Look for grips designed to fit comfortably in your hand. Some models offer interchangeable backstraps for a personalized fit.
- Texture: A good grip will feature aggressive texturing to provide a secure hold, particularly in adverse weather conditions.
Choosing the right grip can make a significant difference, especially during extended shooting sessions.
Buffer Tube and Stock
The buffer tube houses the buffer spring and connects the stock to the lower receiver.
Types of Buffer Tubes
- Mil-Spec: Generally standardized, these tubes allow for broad compatibility with various stocks and components.
- Commercial: Slightly bigger in diameter, commercial buffer tubes may not work with mil-spec stocks or components, so it’s important to know which type you’re using.
Choosing a Stock
Stocks can be fixed or adjustable:
- Fixed Stocks: These provide a set length of pull, offering stability and simplicity.
- Adjustable Stocks: These allow the shooter to customize the length of pull, which can be valuable for different shooting styles and body types.
Magazine Release
The magazine release is a small but critical component that allows the shooter to quickly remove and replace the magazine.
Types
- Standard Magazine Release: Most lowers come equipped with a standard magazine release.
- Enhanced Releases: Some options feature larger buttons for easier operation, particularly in stressful shooting scenarios.
A reliable magazine release facilitates quick reloads, an important aspect for tactical applications.
Safety Selector
The safety selector enables the shooter to switch between safe and fire modes, ensuring the firearm is secure when not in use.
Types of Safeties
- Standard Selector: Most AR-15 lowers come with a standard safety selector.
- Ambidextrous Selectors: These options allow for easier manipulation of the safety for both right-handed and left-handed shooters.
Selecting the right safety selector can enhance comfort and usability during operation.
Take Down and Pivot Pins
These pins hold the upper and lower receivers together, allowing for easy disassembly and maintenance.
Material and Design
- Material: Typically made from steel or aluminum, these pins should have a sturdy design to withstand repeated use.
- Features: Some models include a quick-release feature for rapid disassembly.
Choosing quality pins can improve the longevity and usability of your build.
Conclusion
Understanding the components of the AR-15 lower receiver is crucial for anyone looking to build a reliable and customized firearm. Each component plays a vital role in the rifle’s overall functionality, comfort, and efficiency. By familiarizing yourself with these parts, you’ll not only make informed decisions for your own build but also enhance your shooting experience. Whether you are a novice builder or an experienced enthusiast, knowing your lower components ensures a more satisfying and reliable AR-15 that meets your specific needs.