I noticed that while using Dante's Noctua to try and see if fulmination works on it at all that (it doesn't on primary fire since it has no explosion radius and doesn't seem to work for alt-fire either) and I noticed that although the stats say "very high" for accuracy on both "auto" and "active" (active, for projectile alt-fire), the projectile has very low accuracy and sometimes even fires straight into the ground.
Highly reproducible by simply alt-firing in the air and noticing that the Noctua projectile veers way off-course of the reticle.
EDIT: Seems like it was some one-time bug while testing in the Sanctum Simulacrum.
EDIT 2: It looks like what I'm observing is Noctua's accuracy stat actually scales with fire-rate, as including Gunslinger or Lethal Torrent makes the alt-fire pin-point, while leaving the fire-rate unmodded makes the alt-fire wildly inaccurate
EDIT 3: Evidence