Which is why this is not great for self defense. So it becomes frangible if you hit dense bone like the femur. Okay. When you are making those COM shots, where is the dense bone going to be to make the frangible ammo come about and tear up a lot of soft tissue?
COM...
Ribs? No.
Sternnum? No.
Vertebrae? Likely not at all, but then you have shot them in the spine already. The main body (centrum) of the thoracic and lumbar vertebrae are largely cancellous/spongy bone and not likely to trigger fragmentation. The arches are of denser bone, but there isn't a lot to them.
Scapulae? Potentially if you hit the Glenoid fossa or neck region, but not the blade itself
Branching out, let's see...
Collarbone? No
Ilium of the pelvis? No
Ischium? No
Pubis? No
Sacrum? Yes. If you are shooting through the front, the bullet has already passed through the lower intestines and your cone of destruction from the frangible bullet going through the sacrum is going to be limited because there isn't much tissue behind the sacrum for the fragments to damage.
Appendicular Upper...
Humerus? Not the top portion near the socket (mostly spongy or cancellous bone), but maybe lower on the shaft and definitely the distal end.
Radius? Probably All of it.
Ulna? Proximal end (elbow) only
Hands? Not likely
Appendicular Lower...
Femur? Proximal end and most of the shaft, but not the distal end which is mostly cancellous bone
Patella? Maybe, but then you have already shot them through the knee join and the patella and knee joint are wrecked whether you use frangible, FMJ, or hollowpoint.
Tibia? Likely all of it, though some of the proximal end has a lot of cancellous bone
Fibula? It is virtually all denser bone, but there just isn't that much of it, maybe not enough to cause fragmentation
Feet? Tarsals of the ankle, quite likely, but the metatarsals and phalanges unlikely.
Head...
Head? Possibly on some of the (lower) mandible, possibly the frontal bones.
What does this leave us with? Most of the places where there is really dense bone to trigger the bullet to fragment and do a lot of soft tissue damage aren't in the COM vitals. They are in appendicular locations that you may be hitting because you missed COM. As for the head, great that it might be triggered on the lower jaw or forehead, but a regular defensive hollowpoint bullet would be as effective or more effective in those locations. But if you really want to screw up their arms and legs, might be a fine round, but those aren't generally targeted as a primary defensive shot. Otherwise, it is going to be like shooting ball ammo into the person which isn't going to do nearly as much damage as a hollowpoint.
If you are really sold on using a form of frangible bullet, use one that breaks apart in soft tissue, where the petals come off and create their own little wound channels separate from the core.