i've never hunted with that caliber so can't really speak to it.
.308 , .303brit, 30-06, 7mm rem mag, 338 win mag are calibers I've used or friends have used on hunts I've been on but in 25 years of moose hunting, I don't think any of us have ever shot a moose further than 200 yards. Most were much closer than that even.
Someone here will have experience with the 300 wsm
Scroll down the forum menu and find the Hunting and Sporting Arms section and the Hunting section. A search of 300 wsm in those sections will probably yield some useful info and experiences.