The unreacted Hugoniots of three class 1.3 propellants have been investigated by shock compression experiments. Shock waves were generated by planar impact in a 75 mm single stage powder gun. Manganin and PVDF pressure gauges provided pressure-time histories to 200 kbar. The propellants were of similar formulation differing only in coarse AP particle size and the addition of a bum rate modifier (Fe2O3). All propellants contained 90% solids by weight and HTPB as binder. Results show negligible effect of AP particle size on shock response in contrast to the addition of Fe2O3 which appears to “stiffen” the host material. Within experimental error, the unreacted Hugoniots compare favorably to the solid AP Hugoniot. Five shock experiments were performed on propellant samples strained to induce in situ voids. The material state was quantified by uniaxial tension dilatometry. Experimental records suggest chemical reactivity behind the shock front. These results are discussed and compared to experimental studies ...