I just got my NIB Scar 17S. I go to disassemble it and found what looks like machine markings that have ground down a portion of the magazine well including the pin. Is this normal and if so does anyone know why it's like that? Also, my rear sight has zero positive locking when flipping the aperture (it will flip up/down and not lock into either position). I assumed this was normal until I went to a local shop and played with the one they had which would lock/stay up or down until sufficient pressure was used to change it. Let me know your experiences. Thanks.