It partly depends on the composition of the projectiles
used (lead / antimony), partly what they hit on the way
through and the velocity.

I have heard of Buffalo knocked of there feet by 12 bore
guns including charges stopped dead.

Have a read of the 577 article in DGJ by I think Sherman Bell.
Similar results but on a more spectacular level would be had
with 12 bore.

I don't think you'd have a problem killing DG with it iif the shot is
in the right place and even if just off, the shock from being hit with
such a weight of lead is tremendous.

I notice the difference between a 470 Nitro and a 500 Nitro so 12 bore
would be Greater.

I'd hunt DG with an accurate one if I owned a bore gun.

500 Nitro