An investigation was made to determine tensile and impact properties of investment-cast steels used for small arms components. Tensile bars of 14-inch diameter were cast to finished dimensions. Impact bars were cast to allow for the machining of standard Charpy V-notched specimens. All tensile and impact specimens of each steel were heat-treated simultaneously and tempered at selected temperatures so that four levels of hardness could be obtained. Test results indicated that consistent and reproducible mechanical properties can be obtained for cast components when the castings are adequately gated and heat-treated.