I was mistaken (didn't read far enough, I guess). Elgin did kill an elephant with 180 (+/-) pound tusks in Uganda with his 300 Weatherby using 200 grain Nosler Partitions. This was his preferred "open country" elephant rifle and load. He shot the elephant as it was feeding in the Nile. The first shot wasn't exactly where it needed to be and the elephant turned down river, his second was, reaching the brain and the elephant sank into the Nile. This was on one of Gates' expedition hunts into "virgin" sport hunting country. As the elephant sank out of sight, Jack Blacklaws saved the ivory by swimming down and securing the elepant's tusks with steel cables from the Land Rover. After 5 days or so, the tusks pulled free and were salvaged. They ran into a lot of mischief and theivery trying to get the tusks by to the U.S., which included Blacklaws having to bury the tusks in Uganda to keep corrupt officials from trying to seize them, then the tusks being stolen in shipping and Blacklaws having to chase those all over equatorial Africa. I think Gates got them home after nearly two years.

Gates was an interesting character, there's no question about that.