Reactive mixtures based on nano aluminium and nano- or micron size molybdenum trioxide have been pressed. These energetic mixtures have been tested in the Ballistic Impact Chamber and as an energetic projectile impacting a steel plate. Al/MoO3-based reactive mixtures can be initiated by a controlled mechanical stimulus. The sensitivity depends on deformation velocity, pressing density, addition of fluorine containing binder and particle size. Nanometric mixtures of Al and MoO3 have a shorter time to reaction compared to the corresponding mixtures with micron size MoO3. The sensitivity decreases with increase in porosity. No influence of fuel/oxidizer ratio has been found in the experiments. An extensive deformation is needed before the start of reaction is observed. An analytical evaluation of shear rate cannot be applied as a detailed numerical simulation of the deformation process in PBXN-109 shows.