Abstract: A locking assembly is disclosed for securely holding a projectile within a cylindrical tube. The locking assembly is attached to and associated on an one-to-one basis with a particular cylindrical tube. The locking assembly includes a control rod extending parallel to the center line of the tube. The control rod rotates from an unlocked position to a locked position. In the locked position the control rod will cause a cam to move a shoe into frictionally engagement with a projectile placed in the tube. Also disclosed is a configuration for a plurality of such projectile storage cylindrical tubes and associated locking assemblies wherein the use of available space is optimized.