I love Tikkas, as many of our members know.
However, if you want a WSM cartridge, don't get a Tikka.
Why? Many have confirmed that, while the Tikka in WSM is very accurate, they lose about 200fps given their long throats. As such, shooting a .300WSM in a Tikka would be like shooting a .30-06. Shooting a .270WSM would be like shooting a .270 Winchester. This doesn't seem to be the case with regular magnums or standard cartridges, though, just the WSMs.
So if you are stuck on a WSM, don't get the Tikka.
If you are sold on the Tikka, then get your 300 in a Winchester Magnum, not WSM.
Just thought you would like to know.
Zachary