Royal Ordnance are undertaking a fundamental research programme into the internal ballistics of electrothermal chemical guns. The research is separated into two inter-dependant programmes; numerical modelling and experimentation. The modelling separates the gun into three sections; power supply, plasma generator and gun chamber/barrel. The latter two are modelled using a finite difference Eulerian code, using flux corrected transport techniques in the algorithms. The experimental effort bas concentrated on the fundamental physics of the plasma generator and has been confined to closed vessel experimentation. This paper presents the progress to date.