The AR-15 is one of the most popular firearms in the United States, largely due to its modularity and ease of customization. According to a survey conducted by the National Shooting Sports Foundation, there are an estimated 24 million AR-15s in the United States today. This guide will help you understand each component of an AR-15 and provide tips for building your perfect custom rifle.

Understanding the AR-15

The AR-15 is a lightweight semi-automatic rifle based on the Colt AR-15 design. It consists of two main parts: the upper receiver and the lower receiver. Each of these contains several components that work together to discharge ammunition.

custom building an AR-15

The Barrel

The barrel is one of the most critical components of your AR-15. It significantly influences your rifle’s accuracy and range.

When choosing a barrel, consider the length and twist rate. The length will affect the velocity of the bullet, and thus, its trajectory and energy. A common length is 16″ for a balance between maneuverability and performance.

The twist rate (the distance the bullet travels down the barrel to make one full rotation) affects the stability of the bullet in flight. A common twist rate is 1:7 or 1:9, suitable for a wide range of bullet weights.

Recommendation: Ballistic Advantage Barrels are well-regarded for their quality and performance.

Gas System Components: Gas Block, Gas Tube, and Gas Key

The gas system is what makes the AR-15 a semi-automatic. When a round is fired, some of the gases are redirected back into the bolt carrier group, cycling the action and chambering the next round.

The gas block, gas tube, and gas key need to be correctly aligned for optimal gas flow. The gas block should be secured tightly, and the gas tube should fit snugly into it, with the gas key on the bolt carrier group fitting over the end of the gas tube.

Recommendation: Geissele Automatics offers reliable gas blocks and tubes.

Bolt Carrier Group (BCG)

The BCG is the “engine” of your AR-15, housing the bolt and resetting the hammer. A properly installed and maintained BCG ensures reliable cycling of your rifle.

When installing your BCG, ensure that it moves freely within the upper receiver and that the gas key securely mates with the gas tube.

Recommendation: Bravo Company Manufacturing (BCM) is known for their high-quality BCGs.

Customization Tips and Accessories

Customizing your AR-15 allows you to tailor your rifle to your specific needs. Consider adding a free-floating handguard for increased accuracy, a comfortable stock for better handling, and an optic for improved sighting.

Remember, building an AR-15 requires patience, knowledge, and the right tools. Always prioritize quality parts from reputable manufacturers for a reliable, durable, and safe firearm.

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