I have inherited both a .300 and a .375 H&H made by Holland and Holland c.1955 and between them there is nothing on the face of the earth they can't kill and have done so--whether I'd go after elephant with the .375, even if it's allowed and will accompish the task, I'd still prefer a true stopping caliber of .45+ which I have in a Westly Richards doubles in .470 NE and .476 WR and a .425 WR bolt action all c.1955 as well--when six of my uncles went on safari...
When H&H rounds became scarce I acquired a .300 Weatherby and used that a lot until the scarcity dried up and I've gone back to the H&H as it is very accurate and with a lot less recoil then the Wby or Win mag...Now, that I reload, I don't have that problem anymore except for getting brass, maybe!
You will be hunting with a true classic calibre, nearly 90 years old,
Introduced in Britain in 1925 by Holland & Holland as the belted rimless magnum not to be confused with the .300 H&H Flanged NE...
180 grain Soft Nose Bullet
Muzzle Velocity 2750 ft/sec Energy 3020 ft/lbs BL 26"
220 grain Soft Nose Bullet
Muzzle Velocity 2300 ft/sec Energy 2115 ft/lbs BL 26"
Although you have to go to European ammo makers for the cartridges, I can't remember who made it, but there was a 165 or 168 gr bullet for it that was just devastating on deer and pronghorn at around 3,000 fps...When you get it buy lots of ammo for it, 200, 300 rounds maybe even more between the two/three major loadings and this way you won't run out...you can always have your empty cases reloaded by a friend or a custom loader if you don't do it yourself, which you really should...