Sorry if this has been covered previously, I don't have time to read all the posts; however if people are going to argue that it would be "ludicruous" to suggest that Sheila managed to get upstairs from the first shot, then "ludicrous" also equally has to apply to June and Neville who both were able to get up and move about after being shot in their beds.
June managed to get up and put up at least some token resistance with the presumable final shot between her eyes indicating that the killer was having some difficulty despatching her for good, even after the additional six shots she had received previously.
For those that argue that Nevill was shot in the mouth upstairs, it would have to be concluded that even after receiving such a debilitating wound he still managed to stay on his feet and put up one helluva fight in the kitchen before succumbing to further shots.
So the point I'm trying to make here is that if a single shot is so debilitating for Sheila, then by the same token, both Nevill and June would not have been able to get out of their beds to defend themselves, which they apparently tried to do with equally debilitating wounds.
Hoots!