Determining the time since discharge of spent cartridges found on a crime scene may be very useful in firearm investigations. The potential of small calibre munitions was barely studied in the past and this work did therefore focus on that problematic. The first step was to optimise the detection potential of solid-phase microextraction (SPME) followed by gas chromatography coupled to a mass spectrometry detector (GC/MS). This allowed determining the organic volatile composition of empty cartridges immediately after a gunshot. Identification of 32 detected compounds was confirmed by the analysis of reference substances. Preliminary aging studies over 32 h were carried out on selected target compounds to evaluate their potential to determine the time since discharge of empty cartridge cases.