The 6938 is inside the stock in the barrel channel towards the muzzle end of the barrel in front of TG, yes that is correct. The Na 6 40 is just a little further up the stock, still on the inside under the barrel, towards the muzzle end. Could it possibly be a manufacture date for the stock because the spacing is how it is in the channel of the stock? I have no idea and not knowledgable enough to even be guessing, but just a thought. Thanks.