Abstract: An instrument and method for applying high pressures of short duration, with very little temperature rise in the sample, to disrupt tissue, kill cells, etc., is described. The instrument uses an accelerating piston to apply a strong impact upon a sample contained in a chamber capable of holding the very high pressures produced. Following the chamber is a nozzle section. The nozzle has a receiving end cap with an impact surface and a receiver extension which can vary the distance between the nozzle exit and the impact surface. Depending upon the acceleration of the piston and sample size, a portion of the sample emerges from the nozzle as a hypervelocity jet while the remainder stays in the nozzle. The part of the sample remaining in the nozzle will have been subjected to the pressures built up by the shock wave created when the piston strikes the sample seal.