This seems to be a strange discussion.

We are talking about what to back up with on a Leopard shoot and dismissing a 257 Weatherby as being too light a gun.

Whilst at the same time considering popping it in the first place with a pistol that does not even generate the power of the Weatherby and a firing a solid to boot, which will not set up on said Leopard.
If that shot is placed a little too far back that cat will be hell on legs.

The cat is a thin skinned animal. I would much sooner shoot it in the chest at 100 yards with the 257, which if deer of a similar weight are indicative of. will leave a hole you can get your forearm into.

I would save the pistol to cover my back when I go to the ATM in Jo'burg, which after all, is the sort of task pistols were designed for.

Regards