"Use enough bullet"
Here is a pair of 350-grain Hawk 45-70 bullets recovered from a 300-pound wild pig this weekend. The core from the one on the right exited the pig; the two shots criss-crossed through the chest at odd angles and generally made a mess of things.
On a related and interesting note, the guides at the ranch were telling us that they are now strongly discouraging the use of .223/5.56 for big game animals, as they've had too many "adventures" involving that round. Apparently the only thing worse are the "tactical guys" who show up in their Walmart SWAT gear wanting to shoot wild pigs with their 9mm Glocks.