We present a numerical method derived from the Impulse-Linear Momentum Principle that can be used in the design of impact tools for rock drilling. This method allows the prediction of energy transmission to rock, the profiles of stress, displacement and velocity, all of which are important in the dynamic analysis of such tools. Using the Impulse-Linear Momentum Principle in an algorithmic manner, multibody interaction is simplified, and also different load and boundary conditions such as external forces, initial strains, and initial body separations can be directly considered. The accuracy of the method has been contrasted theoretically with both one-dimensional and three-dimensional FEM analysis, as well as experimentally.