I suspect it tumbled after clipping a rib or sternum.I put one through a decent WT buck at 30 yards ,in and out double lung broadside.He wandered 20 yards off into the bush and was standing all wobbly like a drunken sawhorse,as the rack was so so I put one offhand into his neck an inch below his ear.After cleaning and skinning him the 180gr .30 caliber bullet severed the spinal cord but never made it through the rutted neck muscle.But at least it held together.Harold