Honestly after hunting pigs for over 25 years stick with the known, I suggest a 300 whisper/blackout/wtf with atleast a 220-240 gr or a 12ga semi cut to 18-20 and shoot sabot slugs through a rifled bore. I only hunt them in a stand or with dogs "curr/hound mix" as I am somewhat disabled and taste good to porkers or atleast my chunky wife says I do
If he is stalking as a lot of people do and can be legal and all I suggest a ar in 300w and a short as possible semi 12ga for backup. I can tell you from experience that it helps to have two, especially a 12ga that is good for 75-125 yds that shoots a heavy slug which will rip a pig a new asshole. Since using a 300 in a ar I have only had 3 run when shooting heavy bullets but they were miss shots on my end and could have been avoided.