Abstract: High-load fastener packs and magazine assemblies for otherwise conventional fastener driving tools to greatly increase the magazine capacity. Each fastener pack contains a plurality of fasteners arranged in strips. The magazine is provided on one side with an opening for communication with the fastener pack. The fastener pack is readily attachable to and detachable from the magazine. A spring device within the fastener pack urges the fastener strip nearest the magazine into the guiding channel of the magazine when the adjacent portion of the magazine channel is free of fasteners. A substantially conventional pusher element on the magazine urges the fastener strips forwardly and the forwardmost fastener into the drive track of the tool guide body. Alternatively, the guide body of the tool may be provided with a conventional pulling mechanism to advance the forwardmost fastener in the magazine into the drive track.