FWIW, my R9s Stealth has that same "chip" missing, along with some other scuffs and scrapes inside the frame and a fairly ugly scratch under the left rail. I've put somewhere around 600 rounds through it total, but all of this seemed to occur during the first 50-100 rounds or so. It doesn't seem to impair function at all, and isn't visible when fully assembled, so I haven't been too concerned.