No experience on cats, but on our small black bear, running 100 to 250 lbs or so, I do not believe any of the "hard" bullets would be bad choices when the critters are shot at close range where near muzzle velocity rules and expansion is guaranteed. Comparing weights, I think most leopard would fall in the weight range of our bear so I think some of what I'm saying here might translate. {???}

Thus, on leopard, I would think the same thing. Let's say a long shot at a leopard is 75 meters {I think that is correct??}, the striking velocity of any cartridge pushing an "X"-type bullet at, say, a minimum of 2300 fps at the muzzle would provide sufficient and reliable energy to open the bullet.

I would add one caveat; The "hard" bullets would, IMO, be less than optimum under one condition I have read some leopards are hunted; with hounds. I do have experience hunting bear with hounds and super penetration is for us undesireable when dogs bay up a bear and shots are at bayonet range. o

In truth, almost any caliber will go through one of our smallish bear at close range so the argument is somewhat esoteric. Having said that, fast opening, large bullets are prefered by houndsmen here for such hunting. The .444 Marlin with 240 grain bullets is King and the .45-70 with 300's is Crown Prince. Both of those are absolutely deadly on our small bear at 25 feet and I suspect would be the "Off" Light-Switch on leopard, too. And yes, sometimes those bullets stay inside a bear even when the muzzle blast burns hair.