A recoilless weapon system is provided rear portion, a barrel in movable connection to the rear portion, and a handle portion in removable connection with the barrel and/or rear portion. Further, a ballast payload cartridge is removably disposed within a ballast payload cartridge portion of said rear portion, and serves as a center breach to support a combat cartridge. The ballast payload cartridge may have a side primer disposed therein, which allows a single weapon firing pin to simultaneously initiate both the combat cartridge primer and the ballast payload cartridge primer.