A semi-continuous method for obtaining a composite explosive charge comprising a solid polyurethane matrix loaded with a charge, said charge being in powder form and comprising at least one nitro-organic explosive, said method comprising the following successive steps: - obtaining a pasty explosive composition consisting essentially of the following ingredients: • a polyol pre-polymer, • a polyisocyanate monomer, • a plasticising agent, and • a solid charge in powder form comprising at least one nitro-organic explosive, by continuously mixing a pasty component A' and a liquid component B', prepared discontinuously from said constituent ingredients, - introducing said pasty explosive composition into a mould, and - thermal cross-linking said composition in said mould, and being characterised in that: - said liquid component B' comprises 90 to 99% by weight of said polyisocyanate monomer, - said pasty component A' comprises the whole of the polyol pre-polymer, the whole of the solid charge in powder form and the remaining 1 to 10% by weight of the polyisocyanate monomer, the plasticising agent being distributed without distinction between said components A' and B', and in that the continuous mixing of said components A' and B' is carried out in such a way that the weight ratio component A'/component B' is constant, comprised between 95.05/4.95 and 99.55/0.45. - obtaining a pasty explosive composition consisting essentially of the following ingredients: • a polyol pre-polymer, • a polyisocyanate monomer, • a plasticising agent, and • a solid charge in powder form comprising at least one nitro-organic explosive, by continuously mixing a pasty component A' and a liquid component B', prepared discontinuously from said constituent ingredients, • a polyol pre-polymer, • a polyisocyanate monomer, • a plasticising agent, and • a solid charge in powder form comprising at least one nitro-organic explosive, - introducing said pasty explosive composition into a mould, and - thermal cross-linking said composition in said mould, and being characterised in that: - said liquid component B' comprises 90 to 99% by weight of said polyisocyanate monomer, - said pasty component A' comprises the whole of the polyol pre-polymer, the whole of the solid charge in powder form and the remaining 1 to 10% by weight of the polyisocyanate monomer, the plasticising agent being distributed without distinction between said components A' and B', and in that the continuous mixing of said components A' and B' is carried out in such a way that the weight ratio component A'/component B' is constant, comprised between 95.05/4.95 and 99.55/0.45. being characterised in that: - said liquid component B' comprises 90 to 99% by weight of said polyisocyanate monomer, - said pasty component A' comprises the whole of the polyol pre-polymer, the whole of the solid charge in powder form and the remaining 1 to 10% by weight of the polyisocyanate monomer, the plasticising agent being distributed without distinction between said components A' and B', and in that the continuous mixing of said components A' and B' is carried out in such a way that the weight ratio component A'/component B' is constant, comprised between 95.05/4.95 and 99.55/0.45. - said liquid component B' comprises 90 to 99% by weight of said polyisocyanate monomer, - said pasty component A' comprises the whole of the polyol pre-polymer, the whole of the solid charge in powder form and the remaining 1 to 10% by weight of the polyisocyanate monomer, the plasticising agent being distributed without distinction between said components A' and B', and in that the continuous mixing of said components A' and B' is carried out in such a way that the weight ratio component A'/component B' is constant, comprised between 95.05/4.95 and 99.55/0.45.