The Partition is a great bullet. The concept of a 2 part bullet with a partition wasn't original with John Nosler, the German H Mantle preceded it by a bit.
In practice they tend to shed 1/3 to half of their weight and usually exit. Final expanded diameters tend to be right around 100%. All in all it's a good compromise between fast killing and the closest thing you're likely to find to a guarantee against total bullet blow up. The soft frangible front does the real work of blasting big wound channels and the expanded base is along for insurance against inadequate penetration which occasionally happens with total blow-up. You'd make a bigger hole if you blew the whole thing up, but compromises sometimes have to be made.
You know what else sheds 1/3 to 1/2 of its weight and ends up at 100% expansion while exiting most the time? A Hornady Interlock. Or a Remington Core-Loct. Or whatever they shove in blue box Federal. Or; horror of horrors whatever standard factory ammo is on sale. Those makers of factory ammo aren't as stupid as some think.
What you really get with a Partition is the ability to say "all of the time" instead of "most of the time".
hmantel is the best bullet for leopard and lion but and this is a big but you need to know what they re doing ...