from an engineering standpoint, a buffer will reduce felt recoil and absorb some of the energy of the recoiling carrier's impact by spreading its' energy out over a longer period of time.

the felt recoil reduction is noticeable when the buffertech buffer is installed.

some kalashnikovs do not take kindly to buffers and the reliability suffers...short stroking, mainly.

i have come to believe that a thin, homade buffer that is made from a bicycle inner tube or such is about an optimum balance between reliability and the abuility to absorb some of the carrier impact upon the rear trunnion.