Many people over the years have asked "What is the best rifle to shoot pigs with ?"
The simple answer is "Whatever you have in your hands at the time".
My partners son regularly drops pigs with a .223, and never failed yet for a clean kill.
Over many years, the humble old .22 rf has dropped countless pigs.
I found a clip on Youtube last year that demonstrated (some yanks) dropping young feral pigs from a hide,,,
and they were using a gas powered air rifle.
Straight in or just under the ear, and they dropped stone dead with just the back leg twitching.
So yep, correct range, correct spot, and accurate shot, can produce spectacular results.
I am however a strong advocate for using accepted and recommended calibers when going after specific quarry.
I do not fear death itself... Only its inopportune timing!
I've come to realize that,,,,, the two most loving, loyal, and trustworthy females in my entire life were both canines.