Information obtained from the booklet “The Ability of Firearm Cartridges” compiled by Mr. Fanie Combrink from Magnum Arms South Africa.

RKA is the comparing value of the specific bullet of the most popular calibres and is calculated in the following way:
 
MUZZLE ENERGY (ME) x SECTIONAL DENSITY (SD) x the BULLET WEIHT (BW) retained after impact of the target, calculated according to the bullet retention scale used for popular standard bullet weights of all popular hunting calibers. We cannot say what the minimum RKA value is for every animal and distance at which we hunt because it can never be predicted before. We can say that the RKA values are a way of measuring the ability of different cartridges and bullet weights at the different distances of a well-placed shot.
 
Now that the concept of RKA has been explained it will be applied to popular hunting calibers below:

SMALL BORE
.22 RIMFIRE
 
Bullet weight 35 grain
RKA / 50m 10.0
Muzzle velocity 1150 ft/sec
RKA / 100m 6.0
The .22 rim fire cartridge is a wonderful calibre for target shooting, varmint and all small plague animals such as rats and many more. It is also used for culling in boma’s with a silencer and sub sonic ammunition. It is the caliber most people in Africa learn to shoot with because of the inexpensive ammunition, low sound noise and accuracy.
 

.22 WINCHESTER MAGNUM
 
Bullet weight 40 grain
RKA / 100m 24.5
Muzzle velocity 2000 ft/sec
RKA / 200m 15
The .22 Winchester Magnum rim fire round is bigger in diameter with a longer case than the .22 long rifles. It can be used on birds, rabbits and culling at short distance shooting head shots. It is not a hunting caliber and can only be used as a small varmint round and is useless for body shots even on small game when hunting in Africa..
 
.22 HORNET
 
Bullet weight 45 grain
RKA / 100m 50
Muzzle velocity 2600 ft/sec
RKA / 200m 45
The Hornet is suitable for rabbits, big birds like spur winged duck and Egyptian geese and small varmint. It can also be used for culling and hunting of small game in Africa at short distances shooting head shots because the caliber does not have enough RKA for body shots.
 
.222 REMINGTON
 
Bullet weight 50 grain
RKA / 100m 61.6
Muzzle velocity 3150 ft/sec
RKA / 200m 63
The .222 Remington is a true and accurate varmint calibre and is extensively used for culling in Africa. It is also suitable for small game, cats and other smallish varmint animals but because of the destructive nature of the bullet it is not ideal for body shots on small game when hunting in Africa. It is an excellent target calibre.
 
.223 REMINGTON
 
Bullet weight 55 grain
RKA / 100m 72.5
Muzzle velocity 3200 ft/sec
RKA / 200m 77.5
This cartridge is much more destructive than the .222 Remington and can successfully be used for head shots in culling game in Africa or varmint hunting on animals as large as monkeys.
 
22-250 REMINGTON
 
Bullet weight 55 grain

RKA / 100m 65
Muzzle velocity 3730 ft/sec
RKA / 200m 72
The 22-250 is the fastest flattest shooting modern caliber. It can only be used for head shots when a part of the destroyed bullet will land in the brain and kill the animal. It is useless for body shots or as a bush or short distance hunting rifle caliber when hunting in Africa.. The 22-250 is an outstanding target cartridge.

243 WINCHESTER
 
Bullet weight 100 grain
RKA / 100m 213
Muzzle velocity 2950 ft/sec
RKA / 200m 219
This is a caliber that derived from the 308 Winchester case necked down to a 6mm. The velocity and bullet weight allows this caliber only to be used when hunting in Africa as a plains game hunting caliber for small game.

7mm REM MAG
 
Bullet weight 150 grain
RKA / 100m 337
Muzzle velocity 3020 ft/sec
RKA / 200m 357
 
Bullet weight 170 grain
RKA / 100m 460
Muzzle velocity 2755 ft/sec
RKA / 200m 458
This is a good caliber for the hunting of African thin skinned plains game animals. It is not a very good caliber for the hunting of game in the African bush as too much of the bullet will be destroyed on impact a close distances.
 
30-30 WINCHESTER
 
Bullet weight 170 grain
RKA / 100m 327
Muzzle velocity 2220 ft/sec
RKA / 200m 229
This caliber was the first American small bore cartridge and was used in the model 94 lever action Winchester rifles. It is a very good caliber for the hunting of African small game at short distances. It is often used in African dense bush where short rifle with an under lever action is ideal.

308 WINCHESTER
 
Bullet weight 150 grain
RKA / 100m 301
Muzzle velocity 2820 ft/sec
RKA / 200m 305
 
Bullet weight 180 grain
RKA / 100m 438
Muzzle velocity 2540 ft/sec
RKA / 200m 419
This is a hunting cartridge for hunting in Africa as well as target shooting because of its accuracy. The 150 grain spitser is a good cartridge for hunting of African plains game at medium-long distances. The 180 grain and 200 grain bullets makes a good African bushveld hunting cartridge for small and medium game.

 

30-06 SPRINGFIELD
 
Bullet weight 150 grain
RKA / 100m 307
Muzzle velocity 2800 ft/sec
RKA / 200m 300
 
Bullet weight 180 grain
RKA / 100m 447
Muzzle velocity 2620 ft/sec
RKA / 200m 441
 
Bullet weight 220 grain
RKA / 100m 647
Muzzle velocity 2400 ft/sec
RKA / 200m 627
The 30-06 is the most popular hunting caliber in South Africa and for good reason. The RKA of the different bullet weights differ so much that it is hard to believe that it is from the same caliber. The main reason for that is the 150 grain bullet is almost useless and inaccurate while the 220 grain bullet with that the excellent sectional density is a real killer with the RKA of 647. The 150 grain bullet will usually loose much of its weight on impact while the 220 grain bullet will retain most of its original weight when hunting African game. The 30-06 when shooting a 180 grain bullet is a medium African Hunting caliber but when shooting 220 grain bullets it becomes a big game African hunting caliber. The 30.06 has never been a successful caliber for hunting of African plains game but is outstanding for the hunting of game in the African bushveld with the heavier bullets.
 
300 WIN MAG and 300 HOLLAND+HOLLAND
 
Bullet weight 180 grain
RKA / 100m 428
Muzzle velocity 2950 ft/sec
RKA / 200m 440
 
Bullet weight 220 grain
RKA / 100m 658
Muzzle velocity 2650 ft/sec
RKA / 200m 651
As these cartridges are so close together their calculations are regarded as the same.
With the 300 Magnums we come to true African big game hunting cartridges. The 180 grain bullet is a real long distance killer of African plains game wile the 220 grain bullet is outstanding for bushveld and mountain hunting and a well placed shot will always kill quick and clean.

6.5 X 55 SWEDISH MAUSER
 
Bullet weight 140 grain140 grain
RKA / 100m 361
Muzzle velocity 2750 ft/sec
RKA / 200m 360
This is a “middle of everything else” cartridge with no outstanding qualities but merely a small game cartridge of average performance and killing ability.
 

264 WIN MAG
 
Bullet weight 140 grain
RKA / 100m 328
Muzzle velocity 3200 ft/sec
RKA / 200m 353
The 264 Win Mag is a medium small ultra-high velocity cartridge that is very flat shooting. It is the ideal small game Springbuck, Blesbuck and Black Wildebeest hunting when hunting the plains of Africa. The 264 Win Mag will not be of much use in the bush of Africa as the velocity will destroy a standard bullet.
 
270 WINCHESTER
 
Bullet weight  130 grain
RKA / 100m 278
Muzzle velocity 2950 ft/sec
RKA / 200mv 281
 
Bullet weight 150 grain
RKA / 100m 375
Muzzle velocity 2750 ft/sec
RKA / 200m 373
The 270 Winchester is primarily a long distance cartridge for hunting of small and medium size game and is very effective in open grassland areas of Africa on Springbuck and Blesbuck. It is not popular in bushveld areas and bush hunting of Africa because of the destructive effect of the light bullet at short distance and deflection of the bullet in scrub.
 
7mm MAUSER (7 X 57)
 
Bullet weight 150 grain
RKA / 100m 357
Muzzle velocity 2650 ft/sec
RKA / 200m 358
 
Bullet weight 170 grain
RKA / 100m 452
Muzzle velocity 2430 ft/sec
RKA / 200m 439
The 7 X 57 has been around for more than a 100 years and has proven itself as an excellent military cartridge but also as a hunting caliber. Even though it has been used as a big game hunting caliber in Africa in the past it is not a true big game cartridge but very successful on small and medium game at short distances. It is not a good flat shooting long distance cartridge because it lacks the required velocity. The fairly long bullet is known for good penetration and very popular for amateur hunters and also for ladies because of the low recoil.
 
7 X 64 BRENEKE
 
Bullet weight 150 grain
RKA / 100m 357
Muzzle velocity 2850 ft/sec
RKA / 200m 355
 
Bullet weight 170 grain
RKA / 100m 460
Muzzle velocity 2625 ft/sec
RKA / 200m 459
The 7 X 64 was designed to add velocity to the 7 X 57 and it became popular in Africa hunting Springbuck.

303 BRITISH
 
Bullet weight 174 grain
RKA / 100mv 395
Muzzle velocity 2460 ft/sec
RKA / 200m 381
The 303 British is a military cartridge and has been extensively used for hunting in Africa due to its good killing ability. It is a short distance caliber and was never really used for plains game hunting in Africa.

25-06 REMINGTON
 
Bullet weight 120 grain
RKA / 100m 247
Muzzle velocity 3120 ft/sec
RKA / 200m 258
This caliber is a 30-06 case necked down to .257 by Remington and they created a high velocity cartridge carrying a light bullet. In Africa it is used to hunt small game over long distance and for culling.

8 X 68 S
 
Bullet weight 200 grain
RKA / 100m 479
Muzzle velocity 2950 ft/sec
RKA / 200m 496
 
Bullet weight 224 grain
RKA / 100m 598
Muzzle velocity 2800 ft/sec
RKA / 200m 596
This is an outstanding cartridge for long distance and mountain hunting of big game in Africa and is a real killer with the 200 or 220 grain bullets. It is more powerful than the 300 Magnums and if you want to use the caliber for short distance hunting in Africa you will have to use a premium grade or hard bullet.

8mm MAUSER ( 8 X 57 )
 
Bullet weight 200 grain
RKA / 100m 488
Muzzle velocity 2540 ft/sec
RKA / 200m 471
It is a very good short distance caliber and in Africa it can kill everything up to Eland with the 200 or 220 grain bullet. It has no long distance abilities on the plains of Africa.

338 WIN MAG
 
Bullet weight 200 grain
RKA / 100m 435
Muzzle velocity 3000 ft/sec
RKA / 200m 453
 
Bullet weight 250 grain
RKA / 100m 708
Muzzle velocity 2700 ft/sec
RKA / 200m 698
The 338 Winchester Magnum is by far the best caliber from the USA for hunting in Africa, firstly because of the wide application of the different bullet weights but also because of the outstanding sectional density. In all bullet weights it is flat shooting with outstanding penetration ability. It can be used on any soft skinned animal and the 300 bullet will be good enough for Buffalo and Elephant but because rule have no knowledge it is not allowed on the big five.

9.3 MAUSER ( 9.3 X 62 )
 
Bullet weight 286grain
RKA / 100m 696
Muzzle velocity 2400 ft/sec
RKA / 200m 544

9.3 X 64 BRENEKE
 
Bullet weight 286 grain
RKA / 100m 768
Muzzle velocity 2620 ft/sec
RKA / 200m 687
 
375 H&H
 
Bullet weight 300 grain
RKA / 100m 783
Muzzle velocity 2525 ft/sec
RKA / 200m 691
 
Bullet weight 286 grain
RKA / 100m 962
Muzzle velocity 2620 ft/sec
RKA / 200m 716
The three large bore calibres are very much the same in their performance when used to hunt in Africa and are good big game cartridges. The can all be used on the big five with a risk involved because they do not have what is required from a big five caliber. Not one of them is good enough for a backup rifle when hunting dangerous game in Africa.

416 RIGBY and 500 / 416 FULL METAL JACKET
 
Bullet weight 410 grain
RKA / 100m 1148 1335
Muzzle velocity 2370 ft/sec
RKA / 200m 1016
 
404 JEFFERY FULL METAL JACKET
 
Bullet weight 400 grain
RKA / 100m 1020 1051
Muzzle velocity 2150 ft/sec
RKA / 200m 781
 
4250WESTLEY RICHARDS FULL METAL JACKET
 
Bullet weight 410 grain
RKA / 100m 1148 1226
Muzzle velocity 2350 ft/sec
RKA / 200m 1016
The large bores are meant for hunting all big game and the dangerous big five animals of Africa. The 4 large bore calibres have enough energy to kill all game but lack a little when it comes to a backup rifle needed for a charging wounded Buffalo, Elephant or any other of the dangerous game species of Africa.

458 WIN MAG
 
Bullet weight 475 grain mono
RKA / 100m 1036
Muzzle velocity 2050 ft/sec
RKA / 200m 741
 
Bullet weight 500 grain
RKA / 100m 1124
Muzzle velocity 1980 ft/sec
RKA / 200m 826
 
458 LOTT
 
Bullet weight 475 grain mono
RKA / 100m 1203
Muzzle velocity 2250 ft/sec
RKA / 200m 864
 
Bullet weight 500 grain
RKA / 100m 1305
 
Muzzle velocity 2200 ft/sec
RKA / 200m 1015
 
470 NITRO EXPRESS
 
Bullet weight 500 grain
RKA / 100m 1195
Muzzle velocity 2150 ft/sec
RKA / 200m 861
 
500 NITRO EXPRESS
 
Bullet weight 570 grain
RKA / 100m 1334
 
Muzzle velocity 2150 ft/sec
RKA / 200m 958
 
500 JEFFERY FULL METAL JACKET
 
Bullet weight 535 grain
RKA / 100m 1300 1494
Muzzle velocity 2400 ft/sec
RKA / 200m 1089
 
A big bore in 1850 was a 4 bore (4 balls to the pound of lead) with a diameter of the ball about 32mm. The problem with that was the ability to penetrate at the black powder velocity of while the large frontal area was very poor. These big bores are usually used to stop a charging animal after it being wounded while hunting in Africa. Very often the hunter of the big five in Africa has to shoot a few shots in a very short period of time in order to stay alive. In Africa with the tough game you must have the right caliber for the job or come short. Even if you have the caliber strong enough for the operation and the bullet is not well placed having a doubled barrelled rifle with a second shot, is your insurance policy.