The weapon in question (anshulz semi-automatic rifle) could hold 11 rounds, 10 in the ammunition magazine, and a further solitary round in the breach of the gun...
The idea that we think that the children must have been shot first is an example of guilter propaganda. They prefer that interpretation because it gives rise to the problem of Sheila needing to reload before Nevill and June had been incapacitated.
The intention is to make the defence’s position appear implausible by adjusting the narrative to serve the prosecution. Prosecuting lawyers use that technique almost habitually. At Bambers trial they did it a lot and got away with it.
Similarly, the guilters say that it’s ridiculous that Nevill would have phoned Jeremy, because the injury to his jaw would have made it impossible for him to speak. Of course, if he did phone, it would have been before anybody had been shot.
Again, the fact that there was no blood on the phone is supposed to prove that Nevill never did make a call.
Yet they say that Nevill would have been far too strong for Sheila to overpower, because he was so much bigger and because he was a farmer.
So, it would appear that, although Nevill would have been too badly injured even to have made a phone call, he nevertheless would have found it easy to have taken the gun from Sheila.
I agree that Nevill and June would have been shot first, while the children were still sleeping. This not only makes sense from the point of view of an assailant that wasn’t completely stupid, but also from the nature of the wounds inflicted. The controlled shots to the head would have occurred last, where all the victims are concerned. It’s possible that Sheila returned to Nevill and June to fire more shots after she had killed the boys. The most accurate shots must have occurred last.
You are right, Sheila would have had all the time in the world to reload.