It is, or at least was until fairly recently, still legal to punt gun in England.
Greener says the usual punt gun was 1 1/2" bore, three ounces of powder and a pound and a half of shot; I doubt things are much different now. Carry along a 10 or 12 ga to finish off the cripples.
Jac Weller, who used to do great articles in American Rifleman, had an 8-bore NITRO double rifle. He thought it was made as soon as the physical requirements of smokeless powder were reasonably understood; with steel barrels and strong lockup. But way more powerful than needed for any land animal. He had a PWH decline to shoot it at a target, the guy said it might kick him into a flinch that would get him or a client eaten or stomped in the real world.