Thanks for the been-there-done-that input Ardent.
And good to see our favorite cheerleader for the 375 Ruger showed up!
I had a previous thread where I asked about the difference between the 338 WIN MAG, 35 Whelen, 358 Norma MAG and 9,3x62 and I did some more research to conclude the sentiment that the jump from 338 to 358+ makes much more of a difference than you'd think. My guess is it has a lot to do with the bullets as well as the larger diameter heavier bullets retaining more momentum.
If you want a 338 that does damage like the 9,3x62 and 375s, you need to use one of the fast 338s such as the WBY, RUM or Lapua. Otherwise it's just a 300 WIN MAG that's slower and has more recoil.
@Ardent: What types of rifles were popular with the PHs in Africa (30-06, 375 H&H and 458 WIN MAG), interested to hear about them all.
I've hunted beside these in PH's hands, seen a good many more passed around camp but not in actual use. Guys like Dogleg and c-fbmi, and A-Zone can offer a much greater survey. BUM, Boomer, and all the good fellows in a bracket I can contemplate will have more as well, hopefully they'll stop by.
The three that had stopped legitimate charges to the end / saved buttocks were the .375 M70 (wounded buffalo), the .458 FN (darted / green hunt lion turned bad, they decided against ever trying this again), and the .470 double (lion). The .470 double featured in a video of the incident where the one PH shot a lion off the other PH while it was shredding the former's hand, both the hand and the cat were never right again.
If you ever feel like you're doing in life one day is interesting, meet the guys plying the customer service trade to grumpy Germans and Texans, and following wounded buffalo and lions shot by clients into long grass and thorn thickets for twenty grand a year... but I digress. The other (bottom, hand chewed) PH is now deceased, but because he fell off a balcony drunk not due to hunting dangerous game. I shot most of these, and owned or at least played with the ones I didn't.
.375 H&H Winchester Model 70 (Stainless)
.458 Lott Winchester Model 70 (converted .458 Win)
.470 Nitro double rifle, obscure African maker I can't remember
.458 Win Zastava, customised (new stock, sights)
.458 Win FN '98
If I had to pick a rifle to save my life it'd be a double, in thick bush follow up African context. From a client and hunter's perspective (my own place) I'd say a .375 H&H that weighs 8-9lbs is the ticket. A VERY experienced fellow a son-in-law of whom who's a member here put me in touch with returned from deep, dark Africa (Congo) on a long expedition hunt, he had a .375 H&H. Two fellows who arrived just after had .300 WSMs, they were hunting light game, anyhow their rifles arrived and no ammo. The rifles made good tent poles I imagine, as a .375 Ruger would have too.
All the case design and efficiency, action length, and technology arguments in the world mean little when cartridges are a pain to come by. I
almost would admit the .375 Ruger is superior to the H&H except for two critical details; the Ruger is fat in order to fit H&H power into a standard action, and you'll get one less in the magazine than the H&H, and you'll
never find .375 Ruger outside dedicated gun shops. It's being used in Africa now, some places even use them as the loners, but it's a century behind the cartridge it's chasing and given the popularity of the H&H, and the extra round in the mag, it's never catching up. 9.3x62 is the obscure wat to get to medium bore without the trajectory capability of the magnums. A .338 or .375 Mag can well impersonate a .300, a 9.3 can't, while nobody would say it's ineffective. It's very effective, just a lot less versatile, another one of the reasons I sold mine and never adopted it to my battery permanently.
Forgive the rambling, fueled by scotch and iPhone.
. Also all the published velocities I have seen show the .338 as faster than the 9.3x57 by up to 200 fps in the same bullet weights. I'm sure the 9.3x62 is a great cartridge but the numbers seem to disagree with a lot of what I'm seeing here... 
