Transient three-dimensional (3-D) electromagnetic analyses have been performed on armatures and rails which are intended to be used for high launch energy applications. Coupled magnetic and thermal diffusions were solved within moving armatures in both square bore and round bore rail launchers. Current, magnetic field, body force and temperature distributions in the armature and rail conductors were predicted and compared. The predicted mechanical and thermal loading outputs can be further used for launcher structural analysis and rail cooling design.