Instead of disconnecting our barrel at the base and vacuuming out the riser and manifold, I just put a shop vac into the fire box as a blower and air-blasted out all the
ash. It really helped to have an exterior, horizontal clean out. Make sure any interior cleanups or connections are gaskets so the positive e pressure doesn't blow ash inside. So fast and easy.
We did it on a super rainy day so the ash just washed away into the lanescape like a mild volcanic eruption deposit. You could add a pipe elbow and blow into a filtered bag if your scene doesnt support a dusting of ash.
I tried to search out if someone has already posted about this but didnt find anything.
If this idea is redundant, my bad....