Castable high explosive compositions having a binder system containing plastisol grade nitrocellulose (PNC) and an energetic plasticizer are disclosed. The explosive composition also includes a solid high explosive ingredient, such as an explosive nitramine. Reactive metals, such as aluminum, magnesium or titanium, and oxidizers, such as ammonium perchlorate, ammonium nitrate, or ammonium dinitramide, are optionally included in the explosive compositions of the present invention. The disclosed explosive compositions have a typical detonation velocities above about 8000 m/s.