Pull the bolt back all the way, push the bolt forward all the way--> Bullet gets chambered. If you get nervous and get a hitch in this process, yes, you can have an issue with a jam. Controlled round feeds take care of this issue and are considered more of a dangerous game action for this reason. Outside of those who are new shooters, I have never seen problems with cycling a sako/tikka.
Regarding 300WSMs, they are known to have feed issues in a number of guns, and slight adjustments in mags/feed lips sometimes need to be made. With this said, I have a 300 wsm in a Tikka and have not had issues with shells loaded to various COALs with different bullets/manufactures. It is a fantastic cartridge. I have a couple Tikkas and love them. Accurate, good stock ergonomics, great trigger, good aftermarket support. Wish they had a 3 position safety, but I have not found a perfect gun outside of a custom. I will likely purchase more in the future.