I only carry 2 rifles on my quad when pigs and deer are around, my custom Ruger 25-06, or one of my other 25-06's and, my Rossi lever in 44 mag. The Rossi has a 16" barrel, is stainless, has XS Ghost Ring sights and holds 10 rounds all up, 9 in the mag. I don't know about the US, but here in Down Under, the only solitary pigs are old boars, the rest are normally in groups larger than what ammo my rifle holds.
For the large pigs seen at distance, I use the 25-06 with 110g Accubonds, for mobs I use the 44 with Speer 240g SP Gold Dots, these penetrate like no other handgun bullet I've ever seen.
Anyway, that has worked for me for 20 odd years.
Enjoy your pig hunt, it is very exciting when you get onto a large mob, quick shooting is a must.
Cheers.