It does, actually. You're trying to understand something that you've never seen or experienced before. You're taking a preexisting design and assuming its the same. It is obviously not. The wheel gun of yesterday fired actual ammunition. If this were anything like a normal revolver, you could open the wheel and replace expended ammunition. Instead, you replace the whole wheel. The Destiny Hand Cannon does not have ammunition, instead firing some sort of energy projection...it appears anyway.