MemberMarch 24, 2017 at 7:49 pm1 Bullseye
You want the scope as close to the top of the receiver as possible, which argues for smaller tubes and no rail. If you're hunting with your '06, a scope with a magnification range of 2.5-8 or 9 power is very adequate and these can be had in tube sizes less than 40 MM. You might try the factory rings (I assume they still ship with the new T3x rifles) but if you want to use high quality steel mounts, try these http://warnescopemounts.com/tikka-mounts/
Both the factory rings and the Warne rings screw down tight at the sides of the rings. You do not screw them into the top of the receiver. There is a recoil lug on one of the rings (front one I believe) that must fit into a receiving hole on the top of the receiver. It's what keeps the rings from moving all over the place due to recoil. Look at the photo about half way down this page where Tikka talks about its improved mounting system: http://www.tikka.fi/rifles/tikka-t3x It's the bigger hole smack in the middle of the photo.