I think you have been given some good advice on barrel length and shot size by some very experienced shotgunners, and I agree with what they told you. However, Let me say that there is a great deal of wild boar hunting here in the U.S. lately. For reasons that are essentially unknown, the wild pig population has exploded. Most states consider them a detrimental pest and don't even have seasons on them. They are not classified as game animals. But, back to shotguns. While it is true that a twelve gauge has enormous stopping power on soft tissued game. With 00 buckshot, (you are essentially firing about a half of clip of 9mm pistol bullets every time you pull the trigger). There are about 12 pellets of about 35 cal. in a 12ga. shell. But, the frontal area of a hog has a thick armor-like plate of tissue below the skin that can stop or seriously slow down projectiles. You said yourself that "it took 3 rounds of buckshot." IMHO, that is two rounds too many on a dangerous animal. Most people who hunt hogs use high powered rifles. The 30-30 Winchester is about the minimum recommended. If I was going to use a shotgun, I would certainly load it with slugs. A 12 ga. with slugs will stop virtually any animal. The problem is you have the trajectory of a rainbow. That's alright in close cover with short range shots, but poor in open grassy areas. A wounded boar may very well come straight for you. With buckshot you must be close. Very close. Then if he comes after you, you have very little time for a second shot and will probably never get off a third shot. Remember, I'm talking about aimed shots, not three wild panic shots. There is an old saying here, that goes: "carry enough gun." Meaning a gun big enough to get the job done on that particular animal. Err on the safe side.
