A Deep Dive into AR-15 Lower Parts


The lower receiver of an AR-15 is a critical component that houses the firearm’s trigger group, magazine well, and controls. Understanding the various lower parts is essential for building, customizing, or maintaining your AR15 Parts. Let’s take a closer look at these components:

1. Lower Receiver: The lower receiver is the serialized part of the AR-15 and is considered the firearm by the ATF. It serves as the foundation for all other lower parts and houses the fire control group.

2. Fire Control Group (FCG): The FCG consists of the trigger, hammer, disconnector, and springs. A quality FCG greatly influences trigger pull, accuracy, and overall shooting experience. Upgraded FCGs can provide a smoother and lighter trigger pull.

3. Trigger Guard: The trigger guard protects the trigger assembly and provides a space for the trigger finger. Some AR-15s have a traditional trigger guard, while others have an enlarged, winter-style guard for use with gloves.

4. Pistol Grip: The pistol grip attaches to the lower receiver and is where the shooter’s hand holds the rifle. Pistol grips vary in ergonomics and texturing, allowing users to choose the one that fits their hand and shooting style.

5. Magazine Release Button: This button allows the user to release the magazine from the magazine well. It’s typically located on the right side of the lower receiver, but ambidextrous versions are available.

6. Bolt Catch/Release: The bolt catch is used to lock the bolt carrier group (BCG) back after the last round is fired. It also releases the BCG when a new magazine is inserted. Some upgraded versions offer enhanced ergonomics and ambidextrous operation.

7. Safety Selector: The safety selector is used to engage and disengage the rifle’s safety mechanism. Ambidextrous selectors are available for left-handed shooters.

8. Buffer Tube (Receiver Extension): The buffer tube houses the recoil buffer and buffer spring. It attaches to the rear of the lower receiver and plays a critical role in managing recoil. Different buffer tube lengths are available for various stock options.

9. Buffer and Buffer Spring: The buffer and buffer spring work together to absorb and dampen recoil. The buffer weight can be adjusted to optimize cycling for different calibers or configurations.

10. Stock or Pistol Brace: The stock or pistol brace attaches to the buffer tube and provides stability and support for the shooter. AR-15s can have fixed, collapsible, or adjustable stocks, depending on the shooter’s preference and intended use.

11. Takedown Pins: Takedown pins secure the upper and lower receivers together. Pushing them out allows for field-stripping and maintenance.

Understanding these lower parts is crucial when building or upgrading your AR-15. Each component can be customized to match your shooting style, ergonomics, and aesthetic preferences. As always, ensure compliance with local and federal firearm laws when working with these components.

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