We performed closed vessel tests to study the combustion of several gun pro-pellants ignited classically or by ETC. We analysed the results to estimate the combustion rates and energy losses to the bomb wall. The classical STANAG 4115 method for the determination of the combustion rate of solid gun propel- lants classically ignited was adapted for ETC conditions. The experimental combustion rates obtained were compared with existing more fundamental ex- pressions of this rate by coupling thermodynamic equilibrium calculations with the experimental results. This coupling allows also the estimation of energy losses to the bomb wall. As this research is still underway, we present the more significant results on a double base propellant (NC/NGL...