A capillary extrusion rheometer was used to evaluate the flow behavior of mixtures of nitrocellulose (12.2% nitrogen) and nitroglycerine when processed using solvent blends of different strengths. The aim of the work was to quantify the effects on flow behavior of “gelatinization,” that is, the degree of breakdown of the fibrous structure of the nitrocellulose. The flow behavior was measured over a range of extrusion temperatures. The results indicate that the materials behave as Herschel‐Bulkley fluids, that the shear stress decreases as gelatinization increases, and that viscous heating is more apparent in poorly gelatinized doughs. Surface temperatures of the extrudate determined experimentally are compared with computer‐modelled values. Die swell measurements decreased with decreasing degree of gelatinization and with increasing extrusion temperature.