Not doubting your ability to handload good, but if your gunsmith who blueprinted the action and rebarreled the gun for you was any good then you should have no problem shooting any quality bullet with 1/2" accuracy.
Not at all a true statement.The accuracy of a load is based on many factors and some particular bullets just will not shoot as well as others in a given rifle reguardless of the quality of the rifle or the load development.This applies to all cartridges.not just the large capacity overbore cartridges.