Brenekes and sabot slugs have the hardness, but not the sectional density. A good sectional density is what is necessary for penetration. On hogs, slug guns are plenty, of course, but I get more energy out of my 7 mag and as much from my .308 at the muzzle and either, with a good bullet, will shoot through 4 or 5 hogs lined up end to end. LOL Out to 100 yards or a little beyond, a rifled shotgun with a sabot will work great, but the .308 will work to 400 yards if that were possible, which normally it isn't on hogs, and it will work just as well as the shotgun right out of the muzzle and with 3/4 MOA accuracy, I can drill his ear at 100 yards.
Rifles are my tool for hogs. Shotguns are for the birds, except when I'm forced to use 'em via rules of the WMA. Buckshot is wimpy at any rate, 33 caliber round ball. Out at 20 or 30 yards, a head hit would be highly desirable. Someone equated each pellet to a .32 ACP and that's pretty close to correct, a .33 cal round ball at about 1200 fps, well less than 100 grains in weigh, probably around 50, haven't weighed one. Measure that against a 160 grain Nosler partition at 3100 fps muzzle velocity from my 7 mag or a 150 grain Nosler BT at 2800 fps from my .308 Winchester.
No foster slug can even come close to the penetration and power of even a normal deer rifle, let alone the big magnums. They're big in diameter, but low in velocity and sectional density and provide inferior penetration, don't care what the game wardens use on bears in Alaska. If I lived up there, I'd have me a Browning BLR in .325 WSM, over 4000 ft lbs muzzle energy and big .338 caliber bullets from a reliable lever gun.