RE: What caliber @ 100 yds.
I have a .35 Remington and it is an excellent hog gun. I've shot a 300 lb boar in the shoulder and it didn't penetrate all the way through though the heart and lungs were mush. Most guns we use won't shoot completely through the shoulders at longer ranges though as long as you penetrate the first shoulder it will destroy the heart or lungs. The shield on a large boar can be 1-1/2" thick and is like a armor plate. Though on smaller boars or sows we never had any problems at all.