Sometimes ranged weapons shots/projectiles will phase through a targets head, even if you can visibly see the projectile pass through the head of the enemy.
This happens on warriors, the warrior lords, maulers and stormvermin. I do not have footage of it happening with stormvermin, but it seems to be mostly trying to shoot them from the side.
I made another report specifically for it happening on chaos warriors, but i’m making a new one as the issue is more widespread than i formerly thought.
Link to former post: Some projectile weapons can fail to register a hit vs chaos warriors head
It can be time consuming to reproduce, it seems to happen more or less often depending on weapon and enemy.
To reproduce spawn one of the mentioned enemies and try to shot it in the head. As it seems to be a mismatch between model and hitbox, it’s more likely to happen when the enemy has moved its head recently or is moving its head.
Crossbow bolt not registering on mauler head: https://streamable.com/xijvx
My former post about warriors specifically contains multiple videos of this happening with a variety of weapons.