When it absolutely, positively has to be dead.

In 1978 Grandfather was going on a Kodiak bear hunt. He bought a .458 magnum to use, it was a huge casing, shot a 550 grain bullet. That was pain I never again wish to experience. And it's 1/4 of what that cannon put out.

Like to shoot a hog with it. Just One

Its got nothing on the 2 bore T-rex. This one looks like it will set you back between 75k - 125k though and they have to load it light or the recoil might kill you.
https://www.firearmsnews.com/editorial/tyrannosaurus-2-bore-rifle/365185

That’s just dumb.

No, No, No. I had to sight in a .460 Weatherby for a customer when my dad had a gun shop and I think that is where my right shoulder problems started. I ended up putting a bag of lead shot between the recoil pad and my shoulder when I shot it off of the bench. I probably weighed in at 125#'s and it kicked me like a mule, I can't even imagine what that rifle feels like.

I’ve shot several 8 bores and a rare 6 bore over the years. Tremendous recoil but more a big shove. These were all black powder guns from the 1800 and 1700s.
I have also shot many 416wby and 460wby rifles and they are more punishing than the 8 bores.
Weatherby quit selling 378 and up calibers without a muzzle brake in the early 90s. They are fairly manageable with the brake