SHAKK

Its a weapon used in the TimeLine Wars series of books by John Barnes
(Series consists of:
Patton's Spaceship
Washington's Dirigible
Caesar's Bicycle)

The ammo on this bugger is a translucent bead about half the size of a BB. It finds whatever was in the sights when you pulled the trigger, out to about six miles, at Mach 10.

Upon impact with a living being, it transverses through the body until it reaches the head.

A firsthand account by Mark Strang states:
"I took the shot at his wrist. I saw the hand jerk as the shot entered his arm, and steered up through it, the shock wave making his arm first bulge then collapse. Blood sprayed from the shattered wrist, burst from the shoulder as the shot crossed to his head, sprayed once more as the shot went in through his eye; then used up its remaining energy spiralling around inside his head, turning everything inside into a runny jelly"

Unlike ammunition of today's weapons, the SHAKK take raw materials through a loading drawer, extracting the materials it needs, and disposing of the unused portions in a purified form.