Mine is either a .243 or a .223 . I like to try for shot placement rather than knockdown power. I rarely have a pig run further than 10ft when I make a headshot.
You're right, shot placement is the most important in any firearm situation. Shooting large calibers and hitting something in the foot doesn't work very well. Most any caliber works well when placed in the right spot. A .22 rim fire has put alot meat on the table.