An applicator instrument for dispensing surgical fasteners includes a housing having a cartridge opening, an elongated shaft extending from the housing, and a cartridge insertable into the cartridge opening, the cartridge having a plurality of surgical fasteners pre-loaded into the cartridge. The applicator instrument has a firing system disposed within the housing, and an actuator for activating the firing system to commence a firing cycle for removing one of the surgical fasteners from the cartridge and driving the removed surgical fastener from the housing to a distal end of the elongated shaft. In one embodiment, the cartridge includes a cartridge body having an upper end and a lower end insertable into the cartridge opening. The surgical fasteners are arrayed in a stack that extends between the upper and lower ends of the cartridge body. The cartridge has a constant force spring that normally urges the stack of surgical fasteners toward the lower end of the cartridge body for being fed into the firing system.