A circular stapling instrument is provided which includes a reciprocatingdrive shaft and a firing bar. The reciprocating drive shaft has a firstengagementmember at a tip of the reciprocating drive shaft and a threaded adjustmentmemberat a base of the reciprocating drive shaft. The firing bar is movablyconnected at afirst end with a firing trigger and movably connected at a second end with astapling head assembly through a second engagement member. The firing barforms a first engagement surface which faces a respective second engagementsurface formed on the reciprocating drive shaft. The circular staplinginstrumentalso includes a frictional reducing member located in between the first andsecondengagement surfaces in order to reduce friction between the reciprocatingdriveshaft and the firing bar.
