I would say 3 hits beeing the minimum. But I wouldn't be satisfied with that

When I pattern my gun at 40 yards I usually shot at least 5 shots...

My 5 shots may go something like this

1st 12 hits in vitals
2nd 8 " " "
3rd5" ""
4th 7 " " "
5th 9 " " "

I'll average those out and say I get 8 hits consitently in the vitals at 40 yards...