Blood issuing from a wound to the head from a high velocity bullet will be in the form of high velocity blood spatter. In this form, the blood droplets would be very small, almost an aerosol. The pattern made by these droplets on a surface would be in the form of a circle and the size of that circle would be commensurate with the distance from the exit wound and that surface.

In this picture, the size of the blood droplets on the right front passenger door panel are too large to be considered high velocity blood spatter.