Composite rocket propellants prepared from nitramine fillers (RDX or HMX), glycidyl azide polymer (GAP) binder and energetic plasticizers are potential substitutes for smokeless double-base propellants in some rocket motors. In this work, we report GAP-RDX propellants, wherein the nitramine filler has been partly or wholly replaced by 1,1-diamino-2,2-dinitroethylene (FOX-7). These smokeless propellants, containing 60% energetic solids and 15% N-butyl-2-nitratoethylnitramine (BuNENA) energetic plasticizer, exhibited markedly reduced shock sensitivity with increasing content of FOX-7. Conversely, addition of FOX-7 reduced the thermochemical performance of the propellants, and samples without nitramine underwent unsteady combustion at lower pressures (no burn rate catalyst was added). The mechanical characteristics were quite modest for all propellant samples, and binder-filler interactions improved slightly with increasing content of FOX-7. Overall, FOX-7 remains an attractive, but less than ideal, substitute for nitramines in smokeless GAP propellants.