FWIW, when I frag my hammer corals, I score them with a Dremel sanding disc and then whack them with a hammer and chisel. Of course the flesh is ripped and some of the skeleton shatters/fragments. I give them a quick iodine dip and put them back into the tank. I have not lost one and even some of the chips have grown out. Leads me to believe these can be quite hardy under some conditions. I'd say mine show the best polyp extension and fastest growth when the system has stable Alk, temp, Ca, and flow. I use no carbon, no GFO, no c-dosing and few water changes.