A fully automated improved thermal transient test set is used to measure the thermoelectrical response of a number of different fuze heads. The fitted wire model is used to describe the heat dynamics in the fuze head and to calculate a number of intrinsic thermal properties. These properties are used as input for a parametric analysis of the reliability of igniter systems (PARIS). Comparison of PARIS with firing levels obtained with the classical Robbins–Monro method has been used to validate this new way to estimate the sensitivity of fuze heads.