improved , multiphase , high performance , high energy , extrusion cast explosive compositions , comprising , a crystalline explosive material ; an energetic liquid plasticizer ; a urethane prepolymer , comprising a blend of polyvinyl formal , and polycaprolactone ; a polyfunctional isocyanate ; and a catalyst are disclosed . these new explosive compositions exhibit higher explosive content , a smooth detonation front , excellent stability over long periods of storage , and lower sensitivity to mechanical stimulants .