Of course, some localities have restrictions on caliber usage, but legal restrictions have no bearing on what a cartridge is capable of. For instance, in Africa, most localities specify .375 as the minimum caliber for elephant. But before the laws went into effect, there were many elephant taken with 8x57JS and 303 Brit, both of which are pikers compared to the 300WM.
The 300 mag is an awesome round capable of punching a hole through 1/2 inch plate steel at 300 yards. So if you drop the cross hairs on an animal it will drop.
I hunt Elk, Moose ,and any Bear that is out there with mine. Never had an animal make it 20 feet.
A well placed shot is crucial though.