An old magazine article about a .470NE DR made in Ferlach gives the following information:

C - C at the breech 22,5mm
C - C at the muzzle 20,0mm

Barrel length 64,5cm.

If that 2,5mm is accurately measured, then in this rifle the imaginary bore centerlines cross each other at approximately 5 meters (516cm) in front of the muzzle. In 100m the barrels are in that case crossing some 40cm.

Regards
Saku