Interesting the gun is as new so there is no wear on the date stamp but I think the parkerized finish made it difficult for the stamping to adhere? I know it’s November but only a hint of the year? 1983? (Probably right the 50 T1 in the Vintage Gallery is dated July of 1983). 35 years old no wonder the grease in the tap dried out and froze it.
Yes the Diopter is the one used on the 75. He bought it separately at the time and that made the deal a little sweeter cause these are not cheap and its brand new. Not sure it fits the military theme of the rifle but doesn’t look out of place either?