Consistency error in the Horus Heresy books

Okay this isn't anything of a big deal; only of interest to the nerds who like the Warhammer 40k universe and the Horus Heresy books in particular, so if that doesn't include you you might as well stop reading now.

I'm currently re-reading the novels, something I try to do on the release of the next, and I'm heading through "Battle for the Abyss" Not my favourite but it sets up actions that are resolved in later novels. However upon re-reading about the first meeting between the Ultramarines and the other Astartes aboard the Supply Station my eye was caught by a discrepancy. In the description it is remarked that the World Eaters legion are wearing the older Mark V power armour unlike the Ultramarines who are wearing the newer Mark VI Corvus pattern armour. So what?


Well in the later novel "Deliverance Lost" Corvus Corax of the Raven Guard legion receives a delivery of the brand-new Mark VI Corvus armour named after him as his legion helped develop it. He specifically asks why it is classified as Mark VI as the previous Mark was only IV and is told that they are declaring the current cannibalised armour (made up of what's left over from many different Marks) as the Mark V.

As Battle for the Abyss takes place either before or just after the Istvaan conflict that led to the need for the cannibalisation of armour and the nominal creation of Mark V armour; there's no way the World Eaters could be wearing it (or at least calling it that). Also although it's possible the Ultramarines has some test stock of Mark VI it would be unlikely they'd calling it Corvus pattern.

As I said not a big deal and can be easily modified by having the Ultramarines in standard Mark IV and the World Eaters in Mark III which would actually make more sense as the Mark III armour was designed for heavy frontal protection and would complement the World Eaters style of close-combat melee.

No blame can be placed on either author - that the Corvus armour was named after the Primarch of the Raven Guard makes sense and Battle for the Abyss was published before Deliverance Lost; so it's just the timing that's been screwed up slightly.