30.06 is a large calibre, being shot in the neck would have probably caused a decapitation and not that small entrance wound.
The bullet has such velocity it would have caused an exit wound.
The shot heard was from a smaller calibre. A shot from a rifle would have of that calibre would have created a loud boom with a noticeable echo
Look at what a 30.06 did to a gel head at the 9:02 minute mark
https://youtu.be/e2cv9DSt538