An investigation into the dynamic behavior of explosive opening switches, which are used in power compression circuits for railgun research, is summarized. During switch operation, a primacord is ignited at one end of the switch, and a detonation wave propagates down the primacord along the length of the switch. It is assumed that all locations along the length of the primacord detonate simultaneously, a line detonation. A 2-D Eulerian hydrocode was executed to simulate the early-time dynamics of the explosive switch. Three different opening switch element geometries were considered: a circular external shape with a round internal hole, a faceted (or hexagonal) external shape with a round internal hole, and a circular external shape with a round internal hole that has four internal notches directed along predetermined shear planes. The results provide insight into the pressures, stresses, and strains experienced at various locations in the switch.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>