Your center hits may be the result of your anticipation of recoil if the majority of your shots group at '7'. You should have the gun fired from sandbags to determine if the sights need adjustment. If adjusted and nothing else changes, most of your shots will go center and your anticipatory ones that remain will go to '2'.
The instructor must have wondered if it was the gun or me so he did one and it was dead center. He is a competition shooter.
“Paul Meier 2 cards”
For some reason my laptop won’t load this but I understand it’s quite the trick.