This comes up with the new Book of Rust House Raven Warlord trait Lord of Trials, which says:
Each time an attack is made by this WARLORD, an unmodified hit roll of 6 automatically wounds the target.
This can apply to the relic avenger gatling cannon Endless Fury, which says:
Each unmodified hit roll of 6 made with this weapon scores 2 hits instead of 1.
So... do 6s cause two automatic wounds?