"Capable"
You may have asked the wrong question.

Both are easy to make hits with at 400 yards. The 270 shoots flatter. BUT............ at 400 even with a 270 you have to hold a bit high. If you have to hold 2" over a deer's back or 9" over a deer's back YOU STILL HAVE TO BE CAPABLE OF HOLDING where you need to hold.

So the capability of the cartridge is not near as important as your ability to hold and squeeze a trigger. If you can, you can. If you can't you need to get closer and that's about the shooter/hunter, not the tool he has.