> ...a 6.1 m × 0.3 m tungsten cylinder impacting at Mach 10 has a kinetic energy equivalent to approximately 11.5 tons of TNT (or 7.2 tons of dynamite).

Well, that's a bit underwhelming. Sounds a bit like Russian polonium tea, that is, less like a matter of efficiency, and more like showing off the sheer extravaganza of killing somebody in the most colorful, expensive way.