HALO with AAC flash hider
Regarding an older 2007ish HALO. Any experience on one of these working with either the AAC blackout toothed or non-teeth flash hider?
It won't fit with any of the large-exterior-thread flash hiders (Tac-Ord, AAC, John's Guns, YHM), as the HALO collar won't fit over the larger-diameter "toothed" portion you refer to.
As far as use of the HALO with flash hiders that aren't made as modified Acme-thread suppressor mounts, same standard guidelines would apply: If a flash hider is held to NATO spec of 22mm O.D., concentric to boreline, within appropriate length range, and meets all of the other standard warnings as to whether a flash hider is appropriate (See HALO FH FAQ, Dark Helmet's reply here)) that's the way to find if something is suitable or not.