I just purchased 3 core 51mg7s, one for myself, one for my buddy, and one for a gift for my father(who has a core 101) and I was looking at them and realized two are the same and one has some slight tweaks, so it looks like there must have been a production update at some point, so far I can notice there is a ledge molded into the main frame body on the one, along with that one having a more rounded line guide brass entrance piece. The screws holding the side in are silver and the other two are black, so was interested to see if anyone knows anything about this (I would tag bantam1 if I knew how) looking to figure out which is the updated one which I am guessing would be the ledged one. But I have access to another core 50 and 51 aswell so will take a look at those to see if I can notice some other differences in the coming days