It is likely Bamber fired the first 5 shots into June. Then turned his attention to Nevill.
Once Nevill started moving, he would not switch attention back to June.
Nevill may have woken and started moving while the 5 shots were going into June. Bamber was still able to get two face shots as Nevill was getting out of bed.
So again, no time for any blood to fall onto the bed.