At certain conditions, propelling charges for artillery - either because of their low heat of combustion, a low vulnerability, or due to other reasons - require relatively high initiation thresholds. This phenomenon, combined with large gun chambers, high initial charge densities of materials with granular geometry and low porosity powder beds, give rise to delays and irregularities in the initiation times at various points of the propelling charges. These irregular behaviors or failures in the initiation cause pressure waves within the chambers of the weapons. This paper focuses on experimental studies and tests carried out on the processes taking place in the initiation of propelling charges, which can lead to pressure waves in the bore of howitzers and cannons. Pressure waves during initiation are considered to be particularly dangerous to the safety of users and weapons. The behavior of the initiator systems, the flame volume and its distribution throughout the length of the bore are analysed by means of pressure-time diagrams, obtained from experimental shooting. The data are processed using the standard Fourier transform and the discrete wavelet transform, by means of the Daubechies functions. This allows to identify when these events occur during shooting and to determine some of the causes in order to achieve virtual elimination of the pressure waves.