HK cleverly engineered the kit so most of the gun barrels can be installed from outside after construction and painting — very handy for avoiding broken barrels. However, the ball mounts for the nose guns are molded with the barrels rather than the guns. I found a replacement at my local craft store: perfectly sized metal beads with a hole in the center. These will allow me to assemble the ball to the gun and mount the barrel after finishing the kit. The kit includes spare barrels, so I won’t even need to modify the kit guns.