It gets worse I'm afraid. The following is from the official police account of how JB killed hiis family. It's contained in the report to the Director of Public Prosecutions in November 1985, written with a view to having him committed for trial. Acknowledging that the order of deaths could not be determined with certainty, the report contends that:
"...there were probably ten shots fired in the first fusillade [four into Nevill, one into Sheila and five into June] and the remaining three - two into June's head,one into Sheila's head - were inflicted after Ralph Nevill was killed in the kitchen. Eight shots were fired into the boys - eight cases were recovered in their bedroom. Four shots were fired into Ralph Nevill in the kitchen - namely, the two in his temple area andthe two to the top of his head. Three cartridge cases were recovered in the kitchen. It is therefore reasonable to assume that the fourth cartridge case was carried on the feet of the killer, or possibly a police officer, and deposited on the stairway."
Even this ill advised account features Nevill being shot 4 times upstairs and the casing being transferred from the kitchen to the landing. It's doesn't help you in any appreciable way.
It is an account from unspecified police not forensic experts. Police stupidly suggested that Jeremy still had 1 bullet left but instead of firing it at Nevill he let Nevill escape downstairs and was unconcerned of his whereabouts. This is absurd. The notion he would have no concerns about Nevill calling 999 or grabbing a shotgun and trying to shoot him is absurd. He could even get out of the house and run for help. He needed Nevill dead to inherit and also to get away with the other murders. To let Nevill escape so Jeremy could go wake Sheila and drag her to the bedroom to shoot her is nonsense. Aside from it being absurd we know it didn't happen because Nevill would have had several minutes to try to use the phone or arm himself yet he failed to do either. He just went in the kitchen and waited for Jeremy to come fight with him? Nonsense! Moreover, Jeremy was scared police would be able to tell who died first and last. If it were figured out that Sheila died before others that would harm his whole plot of framing her. Moreover, if she died before her kids that would make them the beneficiaries of June and Nevill and their share would go to their father. So he needed Sheila to die last from the inheritance perspective as well as the for the sake of his framing efforts.
The police suggested a number of stupid things in this case that failed to hold up. It can be chalked up to ignorance or even incompetence.
Most of the shots June suffered were to her right side. The killer was angled to the right of her as firing the rifle for 6 of the 7 shots. The bullets traveled right to left in her body. The police recognized the 5 non-head shots were fired in part of the initial burst. 3 of these exited the body into the bed and the other 2 remained in the body but were fired at angles that preclude the killer walking in the room and simply firing straight at her. Moreover, the 2 that remained in her body caused extensive internal bleeding because her heart was still pumping at the time and she was walking around after these 2 shots were fired.
In order to advance their stupid idea that Jeremy let Nevill be for a while and went to get Sheila they suggested that both shots to June's head were both delivered after she was out of bed when the killer returned upstairs. First of all this is a stupid suggestion because if June had not yet suffered a head wound she would not have simply stayed in the bedroom waiting for Jeremy to drag Sheila in and sit there watching him shoot Sheila then to wait for Jeremy to reload and return. She would have left the room like Nevill did. She would have either tried to go help the twins or to help call for help. Worse yet, the blood on her pillow proves June's head was against the pillow while it was bleeding thus she was in bed when shot in the head.
That severe head wound is why June was never able to make it out of the room. She walked to the other side then collapsed before she could make it out. Jeremy returned and shot her between the eyes to make sure she was dead. He didn't return and find her collapsed then shoot her in the side of her chest and between her eyes, he simply shot her between her eyes.
Both chest wounds have feature a right to left trajectory. The killer and June were both in about the same place when both shots were fired. One entrance wound was higher than the other so it went right to left through the upper lung lodging in between Thoracic Vertebrae 3 and 4 while the other went through the lower lung lodging in Thoracic Vertebra 9. The killer had to be to the forward right of June to be able to deliver these shots. If June had a clock implanted on the top of her head the killer would be between 7 O'Clock and 8:45.
This shows how both chest wounds hit the edge of her body:

This shows the approximate location where the shooter would have to be:
This trajectory lines up with June being on the bed or next to the bed while the killer was at the foot of the bed. The trajectory is not consistent with someone walking back in the room and shooting June to make sure she is dead only the shot between her eyes is consistent with such.
Time and again I have pointed out that the "WHY" is key. What people believe is not important at all. What matters is the why. The why will answer whether the position is credible and supported or not. That people sometimes advance notions that are not supported and incredible merely means people sometimes advance irrational erroneous things.
A totality of the circumstances analysis takes into account everything that is relevant. It doesn't look at limited points in isolation it looks at everything in complete context. When one does that they with respect to this case in order to assess what happens they are left with the shooter attacking Nevill and June, firing 6 shots into June and 4 into Nevill till the gun is empty, the killer running to the kitchen to reload with Nevill following or Nevill somehow getting past the killer and going to the kitchen to try to arm himself, use the phone or get out the door to go summon help, but the killer pursuing him and preventing him from doing any of these things, the killer knocking Nevill out then reloading and shooting him 4 more times, reloading fully so the gun has 11 rounds then going upstairs and using 1 on June between her eyes to make sure she is dead, 8 on the boys and 2 on Sheila.
That police ignored so many things to make stupid suggestions doesn't make their stupid suggestions logical or possible it just scares one that they can be so inept. That doesn't instill great confidence. The kinds of mistakes they made with regard to analyzing the order of the shots could not only result in criminals getting away but can result in charging an innocent person in some instances.