What do you expect? It already tears of arms legs and heads. It's wound channels are not large enough to do any more. (I'm not 100% sure about legs, but I frequently tear off arms and heads and have gone over to the corpses to confirm.)
For example, a .50 BMG AMAX (which fragments btw) creates a maximum permanent cavity of under 8 inches. That will not tear a grown man in two.
Now, a 14.5mm round produces more energy but is also encased in a very, very thick jacket, and will not fragment.
Therefore, the permanent channel will be a factor of both bullet diameter (~0.585 inches) and bullet length (~5.1cm for some 14.5mm I think.)
That's not enough to cause horrific wounds such as splitting people in two or popping them like balloons (thank you, Rambo, for making people even more ignorant.)
So, in conclusion: large, Anti-Materiel rounds usually only take off limbs due to the fact that they strike bone - the round will yaw or fragment when encountering such hard material creating a wound channel that may result in sheering the limb off, but if it were to strike bone on the torso (say spinal cord) the wound would still be incapable of breaking a man in half, and if the round passes strictly through tissue, that while the temporary cavity may be large, the permanent cavity will only be a factor (as stated above) of bullet diameter and length if it yaws.
I have attached an image of a .50 BMG Mk211 round through ballistics gel. It clearly demonstrates that such a powerful round could not do such things as Hollywood would like you to believe.