308 is more than enough with 150,165, or 180 gr bullets. I have successfully hunted porkers for over 20 yrs using 223 (64 gr PP), 243 (100gr PSP), 30/30 (150 gr FP), 30/06 (180 gr), and 45/70 (300 and 400 gr). In addition I have taken many with .50 and .54 cal Muzzleloaders, 44 and 357 Magnums.
Shot placement is everything. I have taken many friends on hog hunts and the most common "miss" or shot that lets the hog run off is 1) too far back, behind the shoulder, missing the lung and hitting the gut; or 2) when trying for a "neck" shot hitting too far back and above.
As you can see from the diagrams, the hogs spine is lower in neck than many other animals. In addition a very feral hog will be "built up" over the shoulders - in essence a big berm of muscle, gristle, and hide over and above the spine. If you are aiming too high you will hit and stun the hog but not anywhere near killing it.
I lost three hogs early on when I first started hunting them. the first was too far back ( I was taking a deer lung shot). the second was too high in the neck/shoulder. The third was a fluke with a very determined sow absorbe a head shot from a 270. She went down and squirmed then got up and ran off. We trapped her about a month later and she had a reverse mohawk down the center of her skull.
These days I pick my shots very precisely that gives me a DRT. Keep using your 308 and pracitce on some hog targets until their anatomy is ingrained in your head for no hesitation on shot placement. then start enjoying the most excellent taste of slow cooked pig.
