A process for preparing a composite pyrotechnic product comprising: a) providing the constituent ingredients of said composite pyrotechnic product, said constituent ingredients comprising: - at least one hydroxyl-terminated polyglycidyl azide, the number-average molecular weight of which is comprised between 700 and 3000 g/mol, - at least one energetic plasticizer, - at least one stabilizer of said at least one energetic plasticizer, - organic energetic fillers of the nitramine type, - cross-linking agents of the polyisocyanate type, - optionally additional fillers selected from oxidizing fillers and mixtures of oxidizing and reducing fillers, - optionally at least one additive, including at least one cross-linking catalyst; b) the constitution of a homogeneous paste, containing all the constituent ingredients of the desired pyrotechnic product; c) casting the resulting homogeneous dough into at least one structure; and d) heat treatment of said homogeneous paste cast in said at least one structure; characterized in that said cross-linking agents consist of aliphatic polyisocyanates: - existing, for more than 99.6% by mass, advantageously more than 99.7% by mass, in the form of oligomers and, for less than 0.4% by mass, advantageously less than 0.3% by mass, in the form of at least one monomer, - having an overall functionality of 2.1 to 3.0, and - used in an amount that ensures a bridging ratio Rp(NCO/OH) of 0.9 to 1.5. a) providing the constituent ingredients of said composite pyrotechnic product, said constituent ingredients comprising: - at least one hydroxyl-terminated polyglycidyl azide, the number-average molecular weight of which is comprised between 700 and 3000 g/mol, - at least one energetic plasticizer, - at least one stabilizer of said at least one energetic plasticizer, - organic energetic fillers of the nitramine type, - cross-linking agents of the polyisocyanate type, - optionally additional fillers selected from oxidizing fillers and mixtures of oxidizing and reducing fillers, - optionally at least one additive, including at least one cross-linking catalyst; - at least one hydroxyl-terminated polyglycidyl azide, the number-average molecular weight of which is comprised between 700 and 3000 g/mol, - at least one energetic plasticizer, - at least one stabilizer of said at least one energetic plasticizer, - organic energetic fillers of the nitramine type, - cross-linking agents of the polyisocyanate type, - optionally additional fillers selected from oxidizing fillers and mixtures of oxidizing and reducing fillers, - optionally at least one additive, including at least one cross-linking catalyst; b) the constitution of a homogeneous paste, containing all the constituent ingredients of the desired pyrotechnic product; c) casting the resulting homogeneous dough into at least one structure; and d) heat treatment of said homogeneous paste cast in said at least one structure; characterized in that said cross-linking agents consist of aliphatic polyisocyanates: - existing, for more than 99.6% by mass, advantageously more than 99.7% by mass, in the form of oligomers and, for less than 0.4% by mass, advantageously less than 0.3% by mass, in the form of at least one monomer, - having an overall functionality of 2.1 to 3.0, and - used in an amount that ensures a bridging ratio Rp(NCO/OH) of 0.9 to 1.5. - existing, for more than 99.6% by mass, advantageously more than 99.7% by mass, in the form of oligomers and, for less than 0.4% by mass, advantageously less than 0.3% by mass, in the form of at least one monomer, - having an overall functionality of 2.1 to 3.0, and - used in an amount that ensures a bridging ratio Rp(NCO/OH) of 0.9 to 1.5.