The AR-15 remains one of the most popular and modular rifles in America. Its unparalleled customizability lets owners tailor everything from accuracy and ergonomics to aesthetics and performance. Whether you're building a home-defense carbine, a competition rifle, or a precision long-range setup, customizing your AR-15 is both rewarding and practical. In this guide, we'll walk through the best AR-15 customization options in 2026, key components to upgrade first, and important legal consideration …