When adjusting a weapon for distance (zeroing), the vertical adjustment is applied in global space. This causes bullets to always travel "upward" relative to the world, regardless of the weapon’s current orientation. If the weapon is tilted sideways (e.g. rotated 30°), zeroing still causes bullets to go upward globally, rather than following the weapon’s own "up" direction. This breaks realistic ballistics behavior, the bullet's trajectory should be adjusted relative to the weapon's orientation. If the weapon is tilted, the bullet should veer off accordingly, following the tilted aim.

Zeroing 800m, weapon vertical

Hit above target

Zeroing 800m, weapon tilted

Hit still above target, but should be off to the right, because weapon is zeroed relative to the barrel dimensions