Every gun is different in relation to "proper seating depth". It simply is what works best in your gun and hopefully it is within the length of your magazine.
I also have a tikka T3 in 300 win mag. My best group is a .9" 5 shot at 300 yds with ammo loaded almost .2" away from the lands because it has a ton of factory freebore.
My recomendation is to take the bullet that matches your animal and load it within magazine length with several powders at near max charges and see what shoots best.
At some point in the future you may want to get a tool that measures the oal of your loaded shell to the ogive. When you find an accurate load I would say to seat other brands of bullets to the same "jump" to the lands of your gun. This has really worked well for me in quite a few rifles.
