Let's say you have unlimited money and acess to all the best tooling and engineers in the world. What do you build first? Here's mine:
Type: Revolver
Caliber: .22 rimfire (interchangeable cylinders for .22 LR and .22 WMR)
Capacity: 12
Action: DA/SA
Cylinder: Swing-out
A real killer would ask about the little red button on the bottom of hte gun.