Riddle me this.

[yakimanoob]

On a serious note, that doesn't sound out of the ordinary at all. Entry-Exit angle could easily be from an imperceptible body angle or from a deflection off a rib (or both). If you did strike a rib, the liver damage could have been from a shard of bone or, as mentioned above, a petal of the bullet shorn off by the impact with the rib.