A M4A1 with a Close Quarter Battle Receiver. The barrel length is 10.3 inches.
Cuted from <a href="//commons.wikimedia.org/wiki/File:M4A1-CQBR.jpg" title="File:M4A1-CQBR.jpg">Image:M4A1-CQBR.jpg</a> with Corel Draw 12