Ready to buy M4 Upper Receiver? Brownells.com carries the widest selection at the best prices on the web. Here, you'll find 159 M4 Upper Receiver and M4 Upper Receiver & Accessories, the best available, at prices from $7.95 to $2,599.99. As the internet's top seller of gun parts and gunsmith tools, we're able to bring you the best products, excellent prices, and reliable customer service every day. We're so convinced you'll be happy with all our M4 Upper Receiver that we offer a 100% customer satisfaction guarantee. If you're not completely satisfied with your purchase let us know so we can make it right. Our entire inventory of M4 Upper Receiver is online, so it's easy to find what you need. When you're ready to order, use our simple cart or call us toll-free at 1-800-741-0015. We're passionate about meeting all your needs for gun parts and gunsmith tools, and we're confident you'll find what you need here. If you have any questions, don't hesitate to give us a call!