A switch on the gun selects the number of chambers used in the shot. Use one chamber, and the bullet is a slow, sub-sonic round that creates no more than a deep bruise. Use all four, and it's as powerful as a normal bullet. These adjustments are made manually and take time. At slow speeds, the gun can fire even the most fragile projectiles.
Further refinements are in the works.
They're also working to integrate a laser range-finder, which would also tie into the automatic speed adjustments. But the applications go far beyond firearms. Taleyarkhan hopes his aluminum oxide chambers will be used in automotive air bags. Tied to a weight sensor in the seat, such adjustable charges could be used to control the force of the inflating bag and prevent passenger injuries. And by harnessing these explosive reactions, this research could eventually save lives.