The invention concerns a method and a device for coring and/or drilling through a wall of a bore hole, to deflect transversely from a longitudinal direction of the hole, further comprising selecting a core barrel (1) equipped with a core bit (3) having an inner gauge bore (5), an arrangement, in the core barrel (1), of an abrasion resistant internal guide (7), which is internal at least with respect to the bore (5) so that the bit (3) can move along guide (7), and is designed to deflect the bit (3) along a desired deflected path, start-up of the coring process with bit (3) and guiding the bit (3) through co-operation between its bore (5) and the guide (7).