Re: Tikka T3 .223 bolt not closing..?
Bolt cycle OK without a round in the chamber?
Any marks on the bullet from the lands?
Check the OAL of the loaded round and see if it is good. If so you may want to have your chamber checked.
One last thing, if it is like a remington and this started after you mounted a scope check the screws and make sure the correct length is in the correct hole.