5/16 inch steel ball ammo has been carefully selected for its special size. Its not too small and its not to large. Ammo that is 1/4" in size is too light and tends to "tear up" wrist-braced slingshot bands that need more weight in the pouch when shot. Steel ammo that is larger than 5/16" is too heavy and is unsafe if used improperly. 5/16" steel ammo is a good balance between light and heavy and it is the ideal size steel ammo for shooting in wrist-braced slingshots. 225 yard range when shot with Trumark wrist-braced model slingshots.