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When shooting pigs with smaller calibres, shot placement is very important. I had a boar a while back that shrugged off a centrefire cal to the shoulder. He was dropped by a 308 to the neck and on...

All three would be able to knock down pigs, but as you suggested they are very much tougher than goats. My first choice would be the 308, followed by the 7.62x39. The x39 wont have the longer range...