Federal needs to amp up its production of HST.
I'd be happy if they just put out the component bullets, too!
I don't think I've seen a gel test where HST hasn't expanded rather explosively, and consistently.
My thoughts on it:
Long jacket notches make for long petals, which makes for large diameters when expanded.
Large diameter hollow point makes for reliable initial expansion, especially through barriers and clothing.
Rapidly tapering hollow point makes for petals with thick bases so they don't rip off or fold back with a tight radius.
I could be totally wrong on what feature makes what happen, but either way, other manufacturers need to start taking notes on Federal HST.
For anyone who's interested check out "9mm Ammo Quest" from 410ShootingTheBull on youtube.