it's either that you're moving or because of 1st shot spread, this shouldn't happen with rifles like vandal, but it does with smgs, some pistols, but most likely
You think the cross hair is on but it's not
you flinch before you shoot and move it.
or like I said 1st shot spread
I'd recommend recording a match and re watching it to see the issue, and also turning on movement error graph from settings