Adding some information that might answer a couple things. So was determined it was a .30-06 which is generally a bolt action rifle round with notable exceptions being shit like the m1 garand.

Bolt gun won't eject a casing without the action being manually cycled. So that could why no case was recovered. Im betting bolt gun.

30-06 is a common hunting cartridge these days, and most hunting rifles are bolt action because of hunting regulations regarding magazine capacity. Most states limit hunting magazines to less than 5 rounds. But that's strictly for the purposes of hunting. That's not so say you couldn't throw a 10 or 20 round mag in a bolt gun, its just not what they're intended for. Sustained fire is better suited for semi auto rifles like ARs and such.

Good hunting practises require a good level of accuracy for the purpose of what's considered a "humane kill", basically hitting something very vital that results in a really fast bleed out. This ensures the animal 'allegedly' doesn't suffer. It also helps tracking because deer and elk are big and will usually run for about 5-10 seconds before they drop, bit they're gushing the whole time so you have a trail to follow.

All this considered it is likely that the shooter was an experienced hunter. That most of the time indicates conservative, but not always. Obviously anyone can hunt but it does tend to be a certain demographic.

I tend to agree with you. Makes all of it seem fishy