A new approach to evaluate fluidity of semi-solid rheo-slurries was developed. The equipment was designed in order to reduce pouring error by using bottom tapping and heated tapping ladle. Commercial AC4C aluminum alloy slurries were tested in spiral sand mold by gravity casting. The slurries were prepared by introducing fine gas bubbles into molten metal above the liquidus temperature at different rheocasting times. Average fluidity and microstructures of cast spirals were reported. Results show that the spiral microstructure is non-dendritic and the fluidity of AC4C alloy decreases with increasing solid fraction. In conclusion, the spiral casting method using bottom tapping can be used to evaluate the fluidity of rheocast slurries in gravity sand casting.