I have been kicking this concept of the finished gunfighter around for a few days, and am probably over thinking the shit out of this, but for what it's worth... I don't think there is such a thing.
I don't mean to get all Parmenides vs Heraclitus, being vs becoming on this, but I think anyone serious about, and dedicated to their profession (in this case gunfighter) would say that there is no end to striving for improvement. There is certainly an improvement to maintenance shift in certain areas (speed, etc) but as Mick pointed out, there are so many elements that compose a gunfighter I think it's silly to be able to say you are complete.
Not that any of that helps us practically... so I gues the complete gunfighter is the guy that makes it home every time.