Has it been threaded,i have seen quite a few problems with newly threaded rifles,infact ive just had that exact problem myself.The bloke who threaded my .222 f****d my crown on my Tikka T3.That could be your problem or you havent mounted your scope/mounts correctly.Take off,strip and re-mount your scope and mounts
I cant see that theres much else to go wrong.It shouldnt need braking in but a few more shots wont hurt
I would try some other ammo.Your rifle just might not like Federal