I found no mention of it in the rules Annex, furthermore is "using an irregular order on himselfe" an point for exiting the fireteam. Is this a intentional nerf if so I would welcome that.
never did IIRC. Being in a fireteam made you non impetuous, no transform you from irregular to regular (except some troops that still do that with a note in the army, like Hungries or Morlocks)
Ah thanks for the heads up it is not in the rules Annex cause it's marked for the specific units. That's the rules awnser I was looking for.