I used an Over & Under double on my first buffalo hunt several years ago. On this safari I was charged by a cow and the gun didn't stopped her (I took the bullet on the boss). I was lucky 'cos the PH used a 500 NE and he did it right. I bought a 470NE as soon I arrived to Europe

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Even a .375 H&H is too "short" to hunt buffs, hippos or elephants, at least a .416 should be used to hunt safely. That's my opinion