A surgical stapling instrument, comprising: (a) an anvil defining a plurality of staple forming pockets; and (b) a stapling head assembly (500, 600) comprising: (i) a body (510, 610), (ii) a coupling member configured to actuate relative to the body (510, 610) to thereby actuate the anvil relative to the body (510, 610), (iii) a staple deck (520, 620) including a distally presented stapling surface (522, 622) having a plurality of staple openings (524, 624), and (iv) a firing assembly configured to drive a plurality of staples against the staple forming pockets of the anvil, wherein the firing assembly comprises: a proximal driving body (552, 652) slidably housed within the body (510, 610), and an array of discrete staple driving segments (560, 570, 660) positioned distal to the proximal driving body (552, 652) and each having a free proximal end, wherein each staple driving segment (560, 570, 660) of the array of staple driving segments comprises a distal staple engagement surface (564, 574) configured to engage a respective staple of the plurality of staples, wherein the proximal driving body is configured to simultaneously actuate the array of staple driving segments to drive the plurality of staples distally against the staple forming pockets of the anvil; characterised in that the staple deck (520, 620) further comprises a stop surface (528A, 528B, 628) configured to engage a staple driving segment of the array of staple driving segments to prevent the staple driving segment from disassociating with the staple deck. (a) an anvil defining a plurality of staple forming pockets; and (b) a stapling head assembly (500, 600) comprising: (i) a body (510, 610), (ii) a coupling member configured to actuate relative to the body (510, 610) to thereby actuate the anvil relative to the body (510, 610), (iii) a staple deck (520, 620) including a distally presented stapling surface (522, 622) having a plurality of staple openings (524, 624), and (iv) a firing assembly configured to drive a plurality of staples against the staple forming pockets of the anvil, wherein the firing assembly comprises: a proximal driving body (552, 652) slidably housed within the body (510, 610), and an array of discrete staple driving segments (560, 570, 660) positioned distal to the proximal driving body (552, 652) and each having a free proximal end, wherein each staple driving segment (560, 570, 660) of the array of staple driving segments comprises a distal staple engagement surface (564, 574) configured to engage a respective staple of the plurality of staples, wherein the proximal driving body is configured to simultaneously actuate the array of staple driving segments to drive the plurality of staples distally against the staple forming pockets of the anvil; characterised in that the staple deck (520, 620) further comprises a stop surface (528A, 528B, 628) configured to engage a staple driving segment of the array of staple driving segments to prevent the staple driving segment from disassociating with the staple deck. (i) a body (510, 610), (ii) a coupling member configured to actuate relative to the body (510, 610) to thereby actuate the anvil relative to the body (510, 610), (iii) a staple deck (520, 620) including a distally presented stapling surface (522, 622) having a plurality of staple openings (524, 624), and (iv) a firing assembly configured to drive a plurality of staples against the staple forming pockets of the anvil, wherein the firing assembly comprises: a proximal driving body (552, 652) slidably housed within the body (510, 610), and an array of discrete staple driving segments (560, 570, 660) positioned distal to the proximal driving body (552, 652) and each having a free proximal end, wherein each staple driving segment (560, 570, 660) of the array of staple driving segments comprises a distal staple engagement surface (564, 574) configured to engage a respective staple of the plurality of staples, wherein the proximal driving body is configured to simultaneously actuate the array of staple driving segments to drive the plurality of staples distally against the staple forming pockets of the anvil; characterised in that the staple deck (520, 620) further comprises a stop surface (528A, 528B, 628) configured to engage a staple driving segment of the array of staple driving segments to prevent the staple driving segment from disassociating with the staple deck. a proximal driving body (552, 652) slidably housed within the body (510, 610), and an array of discrete staple driving segments (560, 570, 660) positioned distal to the proximal driving body (552, 652) and each having a free proximal end, wherein each staple driving segment (560, 570, 660) of the array of staple driving segments comprises a distal staple engagement surface (564, 574) configured to engage a respective staple of the plurality of staples, wherein the proximal driving body is configured to simultaneously actuate the array of staple driving segments to drive the plurality of staples distally against the staple forming pockets of the anvil;