Abstract: Device in a mechanical nailing apparatus including a nail holder to support and guide a nail into position for nailing by means of a nail driver. The device is especially designed for nails (51) which, after being nailed, has at least one laterally expanded anchoring portion (52). The inner cavity of the nail holder (55, 56) intended to receive the nail defines, along part of the nail (51), a guide seat (53) of non-circular section adapted to co-operate complementarily with a guide portion (52) on the nail (51) such that the nail, as it is carried into position for nailing, is given a definitely fixed angle of orientation about its longitudinal axis relative to the nail holder. By positioning of the nail holder, i.e. the nailing apparatus, into a suitable angle for anisotropic materials, e.g. the fibre direction in wood, an expansion nail may be nailed in the angular position where the nail will reach maximum gripping power.