If loading the larger .268" bullets, make sure they are not overly tight in the chamber anb that the ctg. case can release them without them being pinched tightly.
If you fire a regular full power load, then shove a .268" bullet into the just fired case and it fits with a tiny bit of slack (.001" or more)- perfect, you can use the larger bullets as long as your brass does not get thicker.
If it is a bit tight, you can outside neck turn the cases to make them fit properly.