Nevill was shot in the face and jaw upstairs.
Not through the mid brain structure.
Yes i believe Neville was a moving target and harder to kill outright, i don't think he was lying in bed and i dont think Jeremy dragged him downstairs, i think evidence would have shown this with blood dragging and blood runnings/pooling and carpet fibres or friction marks?
It also says this, 44. Daniel had received five wounds from a gun to the back of his head, which appeared to have been fired in an arc and in quick succession. Nicholas had three gunshot wounds to his head.