Those chatter marks on the buffer head technically isnt an issue, but it's the buffer retaining pin. What may cause this as cheaper buffer bodies, not in spec retaining pin or hole, upper receiver and receiver extansion not in spec or slightly out of spec causing the BCG to either travel to far or not far enough. It functions, not a functional issue, however Ive seen a few buffer heads get ripped to shreds in under 1k rounds. If its one of the good milspec buffers with proper coatings and naterial it shouldn't do that, but if it is, id check space in base of buffer tube when the gun is in battery. If the gap is too large aive seen guys throw washers in there ans cleans it up, but a quarter works. Who did the knurling/dimples on that rail? Nice setups. Dont sleep on P4Xi, one of the best LPVOs to date regardless of magnification, great scope!l
