A hydraulic bolt buffer assembly for an automatic firearm, the firearm including a receiver having a longitudinal chamber, a bolt and carrier assembly mounted in the chamber for reciprocating movement between a recoil position and a battery position, a spring for urging the buffer into contact with the bolt and carrier assembly for movement therewith and for biasing said bolt and carrier assembly toward the battery position. The buffer assembly includes a housing having an inner cavity, as well as a piston disposed within the inner cavity of the housing that is movable between an extended position and a depressed position, the piston being in contact with the bolt and carrier assembly. The buffer further includes a spring for biasing the piston in the extended position, as well as a bearing member in fixed relation in the housing and permitting a fluid tight seal with the interior of the buffer housing. The bearing further includes a cavity for retaining an accumulator disposed in a fluid chamber and in which movement of the piston based on movement of the bolt and carrier assembly causes hydraulic fluid contained in a first fluid chamber of said cavity to be moved to a second fluid chamber of said cavity containing the accumulator to slow the firing rate of the firearm.