I have a .318 resizing die but no I caliber rifle in the safe but you never know hat happen in the future.
Got .321 170 grains Speer hot cor bullets from an estate, don't know if they were used to load for a combination gun or a bolt action rifle.
bolt action rifles have much thicker barrels than combination guns so what happen if you use them in a drilling? if kuduae see this - he may have personal experience with such american .321 bullets in I bore guns and will give an advise.