It would seem that both calibres are fine. I am currently looking to move on from a .243 and talked to a gun shop (whom I respect and who sold me the .243) and asked a). if they would take the .243 as part-exchange and b). what (.270 or .308) sold more...thus to give me a practical idea of what (in Scotland) people are actually buying/using. The reply to a). was possibly...or not...because due to the new bullet rules etc. not that many people were now looking for .243s, so fair enough...I'd quite like to keep it anyway as it's a nice SS Tikka M595. Which was all interesting. And for b). they said they sold perhaps twenty .270s for every .308. Which was again very interesting, and helpful.
I would be shooting reds, and perhaps foxes, but not too far out...say at *max* 200m and probably sub-100m. I want to make the deer drop where it is hit as much as possible. And yes, the bullet placement is king (I have taken plenty reds with the .243 so I have seen what that can do and would not be changing if it were not for the new regulations...and that fact that after a few years one becomes itchy for novelty!).
I think I just might pass the decision to the Firearms Officer (I am up for renewal and in the process now so can list the "to be acquired" calibre on the form) and let them decide if they prefer to give .270 or .308 as then the decision is out of my hands as it seems impossible to decide. I know that might elicit groans but it gets the decision made.
Oh go on...if I had to choose, I think it'd be the .308.
One thing, if I may...a few people seem to suggest that the .270 is "more fun". Why, if I might ask...? Does it go BANG in a different way?! Genuine question.