Most likely a very experienced hunter/shooter- Any side-by double, whether a Stevens 311 or a Powell BLE, will usually Not pattern slugs worth a rip- they tend to cross-fire. One reason why the high dollar Limey made double express rifles (Jeffrey, Rigby, Purdey and Holland- are so bloody expensive is the labour to regulate them to shoot to proper point of impact.
The late Robert Ruark advised to "use enough gun" and if I were hunting wild pigs- who can ream you a new one in a heartbeat-I'd go with a accurate 12 gauge pump with a slug barrel-and I'd have it sighted in and know how it handled, where the "go buttons" were.
Here in MI the DNR wants us to shoot during the firearm deer season any and all the pigs we encounter-happy to oblige. Wanna know how tuff "Mr. Makin-Bacon" can be- I use nothing but Remmie 180 Core-Lokt bullets in my old favorite M70 30-06- any buck I punch in the "boiler room" with those great loads usually will stagger a tad and fall, bleeding out- and at 50-70 est'd yards, the entrance hole will be about thumb sized, the exit hole on the other side (at that close range)) will be about grapefruit size- Not so with Porky Pig- I nailed one near season's end- big boar, probably 500 lbs. live wt.- took him in the near shoulder at 35 paces from my stand=-same gun and load, rolled him sideways, but he was still flailing his hooves when I reloaded and walked in from behind his back so I put a finisher in the back of his ugly old haid-and that put his lights out- when we dressed him out, the first shot had broken up his shoulder joint area and that's as far as it went into that heavy hide and layers of tough fat and then hard muscle--
If you want to take your chances with that unknown 20 side-by and slugs, your call- only way I'd trust that bit of armament is if you have cojones enough to shove both muzzles in the porker's maw and then touch off both barrels- Not for me-
