If I were going on this hunt, I would get some of the Gates Tri-Ball buckshot loads. A Tri-Ball is a 3" 12 ga. shell with three .58 caliber round balls in it. Since a .58 weighs 315 grains v. about 54 for a 00, penetration should be better, and they allegedly pattern tightly through a full or fuller choke. This cartridge was developed for precisely what you are planning to do.

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