Like others have said, make sure your FL die is adjusted correctly. How many times have these cases been reloaded? Do you trim your brass after FL sizing?
There's one other possibility that may be causing your problem, but doubtful. The Swift has a tendency to flow brass toward the case mouth. The necks get thick in a hurry! If too much brass has flowed into the neck, it is possible that with a bullet seated, the necks might be tight in the chamber.
This has happened to me using Swifts over the years. Now, I always use a Forster inside neck reamer before I resize the cases. Outside neck turning would probably produce more consistent neck thickness, but it takes longer and the tools are much more expensive!
Thick necks also boost chamber pressure!
F1