I do agree with Guest29835 that Nevill was not in bed or in the bedroom long enough for blood to drip onto his bed or onto the carpet.
It was a rifle for shooting rabbits.
NB was not shot in the bedroom evidenced by way of the totality of the soc evidence: blood stains and lack of, casings, distance of shots, trajectories and wound tracks.
The first shots fired 5/6 were inflicted against June when she was in bed with the shooter stood at the bottom of the bed. NB sustained his 4 upstairs gunshot wounds when stood on the stairs immediately proceeding the main bedroom evidenced by the blood stains and lack of, casings, distance of shots, trajectories and wound tracks.
The soc evidence clearly shows the shooter was in the bedroom with NB coming up the stairs lending support to JB's claim of a phone call ie NB on the phone to JB with the shooter going upstairs, opening fire on June, NB hearing the gunshots and dropping the phone to go upstairs where he sustained his facial gunshot wounds from the shooter firing out onto the landing.