I suppose that as a relatively older hunter (having been going on African safaris for the last 49 years ever since 1974), I can offer a slightly different perspective on this.
Remington Core Lokts were the “Premium” bullets of our time. As a matter of fact, I have been using their 220Gr factory loaded cartridge (out of a .30-06 Springfield rifle) quite successfully on all manners of African plains game over the years (as you can see below). Not just once but several times over, including one-shot kills on bull eland (the largest of the African plains game) and leopard over bait. So I can safely say for certain that my successful results were not flukes.
We had another particularly favorite bullet of mine during our time- The old Winchester Super X soft point (also cup & core in construction). The (now unfortunately discontinued) 175Gr factory loaded cartridge served me extremely well in my 7x57mm Mauser rifle over the years.
Since the 175Gr Winchester Super X soft point for the 7x57mm Mauser is now no longer in production, talking about it is moot. But the 220Gr Remington Core Lokt for the .30-06 Springfield is still in production and I still always voice my preference for this cartridge whenever my outfitters can source a rifle in this caliber for me.
Oh, I’m perfectly well aware of the fact that so many excellent more modern bullet designs are available on the current market today (Barnes TSX, Swift A Frame, etc). And I’ve got absolutely nothing against them. As a matter of fact, whenever a younger novice hunter asks me for opinions on the best bullets for an African safari… I always recommend the most modern bullet choices to them (like Swift A Frames).
But when I myself am personally hunting with a .30-06 Springfield rifle, my preference will still always be for the old 220Gr Remington Core Lokt Cartridge. Why? Because it has & continues to work for me very well. And since I’ve been using it for so long with successful results, I see absolutely no reason to stop using it now.
Herein, I will add that modern isn’t always necessarily better in every context. For leopards & lions (esp. those that are shot over bait), I personally prefer the old fashioned cup & core soft points such as Remington Core Lokts or Nosler Partitions (if you can still find them, that is) or Federal Classic Hi-Shoks over the modern monometal expanding bullets such as Barnes TSX any day.
It must not be thought that I am eschew all forms of modern bullet designs. Nothing could be further from the truth.
During my heyday, my preferred cartridges for hippopotamus (for instance) were RWS 300Gr round nosed steel jacketed FMJ solids and later Remington 300Gr round nosed steel jacketed FMJ solids (fired out of a .375 Holland & Holland Magnum).
Nowadays, my preferences for hippopotamus (for instance) are always exclusively for Barnes 300Gr TSX monometal expanding factory loads and Cutting Edge Bullets 300Gr flat nosed monometal Safari Solids (as loaded by Hendershots Custom Ammunition).