SUCCESS !!! So I punched out the link and pin from the new 9mm barrel and put the link and pin from my original 7.62 barrel in it. Works like a charm. All seems to lock up in battery properly. I put 7 rounds of 9mm in a Tok magazine and didn't bother to try to align the rounds to the front of the mag well (worst case scenario) and they all fed smoothly. I tried to get a round to jam but it wouldn't. I racked the slide slowly, quickly, sideways, upside down and they fed smooth as silk. This solution isn't really what I was looking for as it's a pain to punch out the link each time I want to switch ammo, but it'll do for now.