 Since the beginning of research the United States has funded the XM291 gun project with USD 4,000,000, basic research with USD 300,000, and applied research with USD 600,000.Since then it has been proven to work, although efficiency to the level required has not yet been accomplished.ETC increases the performance of conventional solid propellants, reduces the effect of temperature on propellant expansion and allows for more advanced, higher density propellants to be used.