Sadly, the staple cartridge doesn't live up to the robust build of the stapler itself. Plastic magazine housing appears to be injection-molded in two halves, which are press-fit together once a roll of staples has been inserted. Unfortunately, it appears staples on the roll can be bent during this step in the process. I had to prime several inches of staples before I discovered why nothing was feeding reliably. See photo. It took pliers to pull the bent section through the magazine's feed lips. I think a person without an engineering background would have given up long before the problem was found.