For fun's sake, you can always slug barrels and cast chambers.
As to the auxiliary verb "must", since it is a recently produced modern insert barrel (the cartridges (re-)"invention" itself dates from about 2002), made in Germany and adhering to CIP specifications, it think you can give that answer yourself.

I admit that it would be different for any "7 millimeter", because the US diameters and the Continental diameters for those nominal cartridges differ. But not here.

Carcano