I have reason to believe this is a bug, but part of me also believes this may be intentional. If you shoot an enemy with a sniper rifle using the Graze skill and you hit enemies nearby, it will only count as a 100% accurate shot, and not over 100%, as if you only hit one enemy. However, a shot is still >100% accurate if the bullet directly hits an enemy behind the target. I have never gotten over 100% accuracy with my Thanatos Graze build despite getting massive graze kills.

A small chance this may be intentional as to not hog the most accurate crew stat, but you can get ridiculously high accuracy just using grenade launchers and shotguns. Why not have the same with Graze?

I think it's not a bug, Graze kills aren't made by the actual bullet, so it doesn't count towards the accuracy.

2023 Bump: "Graze" skill still doesn't count towards accuracy.
Easiest map to test: Santa's Workshop.