A cartridge buttress retention system (30) to retain a cartridge buttress material (26) on a staple cartridge (122) prior to stapling of tissue comprising: a staple cartridge (122) including a U-shaped outer channel (108) surrounding a staple containing insert (110); a post (116) formed at a distal end (118) of the staple containing insert (110); distally extending fingers or projections (124, 126) formed in a proximal end (128) of the staple containing insert (110); and a cartridge buttress material (26) retained on the staple cartridge (122).