Countermass liquid for a shoulder launched munition propulsion system

A countermass liquid for a shoulder launched propulsion system that has low corrosivity, high density, low viscosity, and a constant viscosity as a function of temperature. Upon function of the shoulder launched propulsion system, the countermass liquid may be expelled through the breach end of the shoulder launched propulsion system by expanding propellant gas. The countermass liquid may be an organic salt selected from the group consisting of at least one or more of cesium formate and potassium formate.