Fast X is a tagline I started putting in my signature block many years ago. I get asked about it occasionally so here it is.
As originally designed, HunterShooter targets used a flexible overlay for scoring hits and determining target angle. Score zones were designated with a 'V' (vitals), 'Y', and dead center was labeled 'X.'
The final score is a ratio of earned points divided into total elapsed time. The ideal shot is fired dead center as quickly as possible, hence, "Fast X."