Yeah, the 6.5x55 Swede is a fantastic cartridge, and the others are right up there, I think just for kicks, and because I have one I'd go with the 6.5x55mm and never worry.
On the African thing, are you sure you're not thinking about the 6.5x57mm Mauser? and Walter D.M. "Karamojo" Bell, and I think he used a 7x57mm Mauser though many say he had a 6.5x57mm Mauser with him, that he "may" have capped a few with. Just thinking out loud. Cheers
You are correct on the 6.5X57 Mauser. The 6.5X55 has it's share of Game all through Europe and Africa. The 6.5x54 Mannlicher-Schoenhauer was a notorious elephant killer.
I We are big fans of the 6.5. Got my first 260 back in late 90s. Before that it was called the "6.5-08".
Here is an article from Hawks.
The 6.5mm (.264 Caliber) Rifle Cartridges
By Chuck Hawks
It is hard to understand why 6.5mm (.264") cartridges have never really caught on in North America. The more I have learned about the various 6.5's, the more I have come to appreciate them. Most North American hunters are missing out on a good thing, although in recent years the 6.5's have been gaining in popularity and new 6.5mm cartridges have been standardized and factory loaded.
In Europe the 6.5's have been popular since the introduction of smokeless powder during the last decade of the 19th Century. The Europeans evidently recognized a good thing when they saw it.
Whether in standard length magnum form for ultra-long range shooting like the 6.5x68S or .264 Winchester Magnum, true short magnum configuration like the long range 6.5mm Remington Magnum (which duplicates the ballistics of the famous .270 Win.), or standard form like the .260 Remington, 6.5x57 Mauser, 6.5x55 Swede, or 6.5x54 Mannlicher-Schoenauer, the 6.5mm cartridges have much to recommend them.
The recoil of the standard 6.5mm cartridges is moderate, the trajectory is adequately flat for most purposes (including hunting in the mountains or on the plains), and their killing power is generally excellent due to the high sectional density of most 6.5mm bullets. Within their individual ranges, the 6.5mm cartridges are suitable for almost all of the medium to medium-large game animals on earth (game up to about 500 pounds). And even larger animals are within the purview of the 6.5mm Magnums.
The advantage of deep penetration conferred by the excellent sectional density of 6.5mm big game bullets should not be underestimated. It is the secret of the 6.5mm cartridge's success. It is what allows 6.5mm bullets to get deep inside of even large animals, where they can do the most damage.
For instance, the light 120 grain 6.5mm bullet has a SD of .246, the same as a 165 grain .30 caliber bullet. The 125 grain 6.5mm bullet has a SD of .256, equal to that of a 170 grain .30 caliber bullet. The medium weight 140 grain 6.5mm bullet has an outstanding SD of .287, which is essentially the same as a 190 grain .30 caliber match bullet. And the heavy 160 grain 6.5mm bullet has a SD of .328, about like a 220 grain .30 caliber bullet. Ponder these comparisons for a moment and it becomes clear why the 6.5's kill almost as well as the larger calibers, but with much less recoil and muzzle blast.
That the 6.5mm cartridges are suitable for most of the world's big game cannot be disputed. The record of the 6.5mm cartridges in Africa, for example, is well documented. 6.5's became the favorite cartridges of many well-known professional hunters in Africa, a number of who wrote about these cartridges. The legendary ivory hunter W.D.M. Bell was among these, and he went so far as to use his 6.5x54 Mannlicher-Schoenhauer with 160 grain solid bullets for brain shots on elephants. He liked the moderate recoil and the deep penetration of the 6.5mm bullets. He also used the 7x57 Mauser with 175 grain solid bullets for the same purpose. With these two calibers he is reputed to have killed over 1000 elephants.
This is not to recommend any 6.5mm cartridge for pachyderm hunting. The point is that the 6.5's are very efficient cartridges with excellent killing power. In the hands of a good shot they are adequate for game from the size of the smaller African antelope and North American javelina up to Canadian caribou, Swedish alg, Spanish red stag, and African Hartebeest.
As demonstrated in Africa by Bell and a slew of other professional hunters, the benefits of low recoil should not be taken lightly. Less recoil makes for more accurate shooting, that is a fact. Good bullet placement is by far the most important factor in killing power. If a hunter can get almost any reasonable bullet deep into the lungs or heart of an animal, that animal is not long for this world. 6.5mm rifles make it easier for hunters to do just that.
Due to their high killing power and relatively low recoil, the standard 6.5mm cartridges are particularly well suited for the popular lightweight hunting rifles called "mountain" or "scout" rifles. When an lightweight, fast handling rifle is combined with a light recoiling but effective game cartridge that the average hunter is able to shoot accurately, the result is liable to be a lot of game taken. That is perhaps the best recommendation for 6.5mm hunting rifles.