A staple cartridge unit configured for use with a surgical stapler, comprising: (a) a cartridge housing, wherein the cartridge housing includes: (i) a deck, and (ii) a plurality of openings formed in the deck, wherein the openings are configured to house a plurality of staples configured to be driven distally from the openings and into tissue positioned against the deck; (b) a knife movably disposed within the cartridge housing, wherein the knife is configured to be driven distally from the cartridge housing and through the tissue positioned against the deck; (c) an anvil arranged distal to the cartridge housing, wherein the anvil includes: (i) an elongate slot, and (ii) a plurality of staple-forming pockets disposed along the elongate slot; (d) a cutting washer fixed relative to the anvil, wherein the cutting washer includes a cutting portion disposed within the elongate slot of the anvil, wherein the knife is movable distally to cut tissue against the cutting portion; characterized in that: the cartridge housing further includes a first detent feature, and in that the anvil further includes a second detent feature supported by the cutting washer, wherein the cartridge housing is selectively actuatable relative to the anvil between a proximal position in which the deck is spaced proximally from the anvil, and a distal position in which the deck is configured to clamp tissue against the anvil, wherein the first and second detent features are configured to cooperate to releasably retain the cartridge housing in the proximal position. (a) a cartridge housing, wherein the cartridge housing includes: (i) a deck, and (ii) a plurality of openings formed in the deck, wherein the openings are configured to house a plurality of staples configured to be driven distally from the openings and into tissue positioned against the deck; (i) a deck, and (ii) a plurality of openings formed in the deck, wherein the openings are configured to house a plurality of staples configured to be driven distally from the openings and into tissue positioned against the deck; (b) a knife movably disposed within the cartridge housing, wherein the knife is configured to be driven distally from the cartridge housing and through the tissue positioned against the deck; (c) an anvil arranged distal to the cartridge housing, wherein the anvil includes: (i) an elongate slot, and (ii) a plurality of staple-forming pockets disposed along the elongate slot; (i) an elongate slot, and (ii) a plurality of staple-forming pockets disposed along the elongate slot; (d) a cutting washer fixed relative to the anvil, wherein the cutting washer includes a cutting portion disposed within the elongate slot of the anvil, wherein the knife is movable distally to cut tissue against the cutting portion; characterized in that: the cartridge housing further includes a first detent feature, and in that the anvil further includes a second detent feature supported by the cutting washer, wherein the cartridge housing is selectively actuatable relative to the anvil between a proximal position in which the deck is spaced proximally from the anvil, and a distal position in which the deck is configured to clamp tissue against the anvil, wherein the first and second detent features are configured to cooperate to releasably retain the cartridge housing in the proximal position. the cartridge housing further includes a first detent feature, and in that the anvil further includes a second detent feature supported by the cutting washer, wherein the cartridge housing is selectively actuatable relative to the anvil between a proximal position in which the deck is spaced proximally from the anvil, and a distal position in which the deck is configured to clamp tissue against the anvil, wherein the first and second detent features are configured to cooperate to releasably retain the cartridge housing in the proximal position. a second detent feature supported by the cutting washer, wherein the cartridge housing is selectively actuatable relative to the anvil between a proximal position in which the deck is spaced proximally from the anvil, and a distal position in which the deck is configured to clamp tissue against the anvil, wherein the first and second detent features are configured to cooperate to releasably retain the cartridge housing in the proximal position.