We have designed a gas gun capable of delivering a projectile on target within a time window of 60 &mgr;s, and up to velocities of 182 m/s. The gun uses a prepressurized brass projectile held in place with a glass rod in compression. The glass rod is fractured at a precise time using an explosive detonator. Performance calculations were conducted using a simplified model, and the predictions compare favorably with experimental data. ©1996 American Institute of Physics.