We know nothing of the kind as far as the order of deaths is concerned. Admittedly ballistics is not my strong point.
The information I cited previously speaks to order.
The markings on the casings and the bullets recovered tell us the caliber of weapon used and what type of gun was used.
The order of the shootings and then what you raised about whether there wa smore than 1 wepaon used are different issues.
The location and angle of entry of a bullet determines how big an entrance wound will be. They vary. You can't determine the caliber of the bullet by the size of the entrance wound. You need to find the bullet to determine the caliber. Shell casings also tell us what caliber of wepaons were used.
In this case there were 25 .22 caliber bullets and 25 .22 shell casings and 25 wounds. So we know the wounds were all caused by a .22 caliber. The casings were matched the the Anschutz and so were a majority of the bullets. because of the shell casings were matched we know it fired even the bullets that were too damaged to match to any particular weapon.
as for the order the 11 shots in the bedroom and that fact Nevill escaped tells us that was the first shooting scene. 11 rounds would only be used the initial time the weapon was used. (one in the chamber, 10 in the magazine) The weapon had to be empty of Nevill would not have ende dup in the kitchen. It still had to be empty as they fought in the kitchen or the killer would have shot Nevill instead of beating him. He was beaten unconscious so the killer could reload in peace and then finished him off.
At that point 15 rounds had been fired. The killer reloaded the magazine fully. All 10 of these rounds were fired. 8 into the boys and 2 into Sheila. This is where the uncertainty lies. Was she shot first or the boys? The evidence doesn't tell us that. If she were the killer she would have to have killed them first and herself last. But if Jeremy was the murderer he could have done it in either order so only he could answer.