From the 2002 appeal.
43. Mrs Bamber was bare footed and dressed in a nightdress. She had received seven gunshot wounds, of which one to her forehead and one to the right side of the head would have caused death very quickly. She also suffered shots to the right side of the lower part of her neck, the right forearm, two injuries to the right side of the chest and to the right knee. There was a great deal of blood on her body and clothing and from its pattern, it appeared that at some stage of the attack she had been in an upright position.
This has some interesting forensic points.
June was certainly shot in bed. The state of the blood stained pillow highlighting this. June was barefooted and in her nightdress. This shows June was asleep when receiving her first salvo of shots. As the twins were. This highlights Bamber as the killer.
The opening shots may have been in the neck and right side of her chest and forearm. Together with a shoulder shot. Bamber shooting her in the forehead and left side of the head after returning upstairs.
June was also shot in the knee, maybe Bamber wanted to make sure she would not start walking. Or he shot June in the knee after she started moving out of bed.
Two of the shots would have caused death very quickly. So may have been fired after Bamber returned upstairs and saw that June had moved. However he had enough bullets to fire seven into June and four into Neville in one go. There is no reason why he wouldn't release all bullets in one go. Death quickly' may just mean June had the chance to move a few feet.
The options are the gun had ten bullets in. Bamber shot June six times, and Neville four. When Bamber returned upstairs, June had moved a few feet. She was then shot in the reported upright position, in the forehead.
Or Bamber unloaded all seven bullets into June in one go. June struggled a few feet before dying.