What X power at the range (.30-06 @300yds)
 

I need a spotting scope to see a bullet hole, .30-06 @300 yds, at the range. What X power do I need?

Well, it isn't totally a question of magnification....
It's never that easy, is it?
Actually, what you need is definition, or resolving power (the ability to see detail)
In a really cheap scope, you may not be able to, regardless of power.
In a really excellent scope, 20X may be sufficient. In a more moderate priced scope, you may need 30 power.
And, it somewhat depends on your eyes, too.
Told ya it wasn't that easy :(