This report presents the work done in CFD development for gun interior ballistics during 2016. This work builds on and expands the work done during 2015. In propellant combustion a method of simulating the combustion of individual grains of propellant, including complex mixes of radiation, complex chemistry, gaseous ow and phase changes has been tested. Two methods have also been implemented to manage the movement of the projectile wihtin and just outside the barrel. One of the methods has been implemented for use in studying muzzle devices.