If you've been thinking about building your own AR-15, you're not alone. Whether you want the best AR-15 for home defense, a budget-friendly build, or a custom 300 Blackout AR, building your own rifle gives you full control over every part. This guide breaks it all down in plain English — no fluff, just what you need to know. What You Need to Build an AR-15 Building an AR-15 comes down to two main pieces: the upper receiver and the lower receiver. The lower receiver is the only part legal …