a surgical instrument for being endoscopically or laparoscopically inserted into a surgical site for simultaneous stapling and severing of tissue includes force adjusted spacing between an upper jaw and a lower jaw so that the height of staple formation corresponds to the thickness of the tissue , yet does not exceed the height range that may be accommodated by the length of the staples . in particular , resilient structures are formed into an e - beam firing bar that includes a cutting surface that severs tissue between a top pin that engages the anvil and a middle pin and lower foot that engage the lower jaw . the resilience responds to the force exerted by clamped tissue to vary the spacing .