I always imagine the name as the presenter of Rainbow finally cracking and massacring Zippy and George.
That aside. This is the corrupt storm bolter that you get from the Chaos temple in the Meridian spires. It has 70 damage, a melee damage boost and a cool unique model. Interestingly it also has rate of fire 8/10 as opposed to 6/10 for a normal storm bolter (which it even reflects in the equipping animation).
This should make it utterly awesome, especially as RoF does not appear to be linear (compare the different melee weapon types and you'll see what I mean). However, the stated damage is not that amazing, especially when compared with say Twin Testament of War, which has RoF of only the regular 6/10 but doesn't reload. TToW has much higher stated damage output.
Can anyone explain this anomaly?
Even if the stats are right, I'd hyopthesise that CoG has higher burst damage but TToW has higher damage over a sustained period. That would make CoG better for offence and TToW better for defence.