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 (anvil) and a lower jaw (staple cartridge engaged to an elongate staple channel) 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 (knife) 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.