I too have suffered this Phenomenon. Some cracked 360 degrees finger to finger, which makes more sense. Others cracked 360 degrees away from any drilled holes.
AMF Nighthawk Revenge
AMF Nighthawk M/2
Ebonite Vortex Afterburner
Ebonite Pantera
Columbia Beast with Mica solid
I don't know the actual cause. Like Mike said, they will sometimes just crack, even in a controlled environment.
Very expensive and usually at an inopportune time.
“I hate it when that happensâ€.