If you ever skin one out you will know why they are hard to kill. That shield, everyone talks about is why. It's solid gristle,
You can hardly cut through it with a sharp knife. It also contains a lot of fat, which has a tendency to clog the entry and exit wounds.
Like someone suggested, look at the hog shot placement
Pics on here. The very best shot placement on a hog is broadside, straight up the leg and low, you can't shoot a hog too low.
With your set up, two blade broadheads are the he only way to go. Last, if you got a fatal hit, don't giveup on the search, get down on your hands and knees if need be. There is sign there, you just have to find it.
RW