The choice for a certain caliber should be done mainly based on the ability to shoot it properly and the personal preference. As for any other hunt, the first shot placement is crucial. This fact does not change due to a larger caliber!
A lighter caliber can be a better choice to decrease the risk of a poor first shot placement. Additionally, shooting of larger calibers has to be trained. If the cost of ammunition is an issue, you should ask yourself if a Safari is the right choice.
This list is not exhaustive.
Three figures that can help to understand the ballistics of a certain Cartridge:
A bullet's Sectional Density is the mathematical expression of its weight in pounds divided by the squares of its diameter in inches. Sectional Density is quoted as a three figure decimal. It conveys how well an object's mass is distributed by its shape, to overcome resistance. For illustration, a nail can penetrate a target medium with its pointed end first with less force than a coin of the same mass lying flat on the target medium. The greater any bullet's Sectional Density, the better will be both, its down-range and its terminal performance. For dangerous game, a Sectional Density of at least at .300 is recommended.
Example: 375 H&H with 300 Grain bullet
300 Grain = 0,0428571 Pound
0,375² = 0,140625 in²
0,0428571/0,140625 = 0,3047616 = SD: .305
There are however, limits to the Sectional Density. Bullet's that are excessively long and do not open up properly (i.e. Solids) tend to bend or tumble after encountering some form of fairly resistance.
Pondoro Taylor was Africa's first ballistics-thinking big-game hunter. He devised his now well-known "Knockout Value" theory when he realized the Muzzle Energy values were misleading when determining a caliber's dangerous game potential. A bullet's KO value can be calculated by multiplying together its weight in pounds, its velocity in feet per second, and its diameter in inches. While not 100 percent mathematically correct (bullet frontal surface area would have been more appropriated than diameter), Taylor's KO value are a good indication of hitting "punch" and the shock effect.
Example: 375 H&H with 300 Grain bullet
0,0428571 Pound x 2,550 fps x 0,375 = 40,98 = 41 KO Value
Any given bullet needs a certain velocity to work as expected. Nevertheless, too much velocity can have a negative impact to the expected performance. The bullet will probably not develop as expected or will travel through the animal and kill or injure another one, staying behind. The KO value also gives an indicator for that. When a bullet reaches its "optimum velocity", its produces a KO value that will change very little despite further increases of muzzle velocity. As an example: the 375 H&H with 2,550fps will give a KO value of 41 whereas a 375 Remington Ultra Magnum with 2,750 fps will only increase to 44.
(Source: Kevin Robertson; Africa's Most Dangerous)
375 Holland & Holland
375 H&H left, 308 Win. right
The .375 Holland & Holland Magnum as well as the Flanged version are medium-bore rifle cartridges. Introduced by the British company Holland & Holland in 1912. It initially used cordite propellant, which was made in long strands - hence the tapered shape of this cartridge, which also ensured smooth chambering and extraction from a rifle's breech. Both cartridges, the rimless as well as the rimmed have similar performance figures.
In many regions with thick-skinned dangerous game animals, the .375 H&H is seen as the minimum acceptable caliber, and in many places (primarily in Africa), it is the legal minimum for hunting such game.
With relatively light bullets in the region of 235 to 270 grains (15 to 17 g), it is a flat-shooting, fairly long-range cartridge ideal for use on light to medium game e.g. plains game. With heavy bullets of 300 grains (19 g) and greater, it can be used also for large game.
Nevertheless, the .375 is located at the lower range of African cartridges and has its place surely for plains game hunt. When it comes to African dangerous game, it miss often the "punch" effect. The animal is fleeing without any notice of a hit.
Due to the small caliber diameter and the high velocity, the bullet also tends to travel complete through the animal. This is an important fact to take into consideration before the shooting, to avoid injuring a second animal at the background. Especially an unknown wounded buffalo can be a risk for life.
For buffalo or other large game, I would recommend to take on of the 40th calibers with a higher KO Value.
416 Rigby left, 308 Win right
The .416 Rigby was developed and introduced by John Rigby in 1911. In that time the era of black powder run out and the new era of smokeless propellant (cordite) had just started. Ivory hunter received unlimited ivory concessions and the ivory industry was on the way to its peak.
Therefore, it was not surprisingly that the .416 Rigby became a big success. With cordite as a propellant, the original load pushed a 400 gr bullet at about 2,300 fps generating 4,800 foot pounds of muzzle energy, which was nearly twice the velocity of the big bore black powder cartridges of the day. These significantly higher velocities enabled the use of smaller diameter bullets and resulted in bullets with a much higher sectional densities e.g. .330 with a 400gr bullet. This increase of the sectional density made the penetration much more reliably compared to the old big bore calibers.
Due to the large case capacity, the Rigby was doing the job with low chamber pressure. Unfortunately, the case length of 2.9", as well as the base diameter of 0.589" was to long for a standard bolt-action rifle. The German company Mauser was the first one who build an action to accept the new cartridge.
A hunter equipped with a Mauser rifle could fire as many as five shots before emptying the magazine, compared to only one or two with earlier rifles.
The .416 Rigby cartridge has with 63 ft-lbs a relatively stout recoil, which is mild compared to the recoil of the big bore cartridges that it was designed to replace. Nevertheless, it is still more than the recoil of a .375 H&H.
The largest elephant hunted, with a shoulder high of 14,12 feet was shot with a .416 Rigby.
1909, the era of African safaris was in full swing. Jeffery had great success with their .450/400 Nitro Express cartridges, and needed a cartridge of similar performance that would work well in a bolt-action rifle. Using a rimless case of similar design, but changing the bullet diameter from .411" to .423", the .404 Jeffery was born.
The .450/400 NE, which was the benchmark performance level, had gained a reputation for being a very efficient caliber. The 400 grain bullets delivered 3918 ft-lbs of energy at the muzzle, and the high Sectional Density of .338 ensured the bullets penetrated wonderfully. Many noted hunters, e.g. John 'Pondoro' Taylor and Col. Jim Corbett, came to rely on the .450/400. Therefore, Jeffery wanted to have the same performance in the rimless design.
The .404 was an instant success. The mild velocity, and correlative mild recoil, made it easy for hunters to deliver the bullet in the right place. The cartridge fits, with some gun maker's work, in a standard 98 Mauser action and with the 9° shoulder it fed reliably. Dangerous Game rifles were one of the sudden for everybody affordable.
The 400 grain bullet was now traveling with approx. 2,325 fps and generated just over 4,800 ft.-lbs of muzzle energy. Shots out to 200 yards were now easy to make and with a KO value of 47 it had a good immediate shock effect. The older loads, with 2,150 fps, still make a fantastic choice for the recoil-sensitive hunter that enjoys the thrill of dangerous game without the punishment associated with some of the bigger and faster cartridges.
The Colonial game departments of East Africa issued Vickers bolt-action rifles, chambered to .404 Jeffery, to all of their game scouts, but the typewriter of Mr. Robert Ruark launched the much less-used .416 Rigby into fame and glory. At any rate, the .404 Jeff has earned a very reliable reputation in the older piece of Africana, and that is well deserved.
The well known Elephant hunter Kai-Uwe Denker used a Mauser 98 in 404 Jeffery for his hunts as professional hunter.
The Chadwick Ram, the largest stone sheep ever taken and considered to be the greatest North American trophy ever, was shot in 1936 in the Muskwa River drainage of British Columbia, with a .404 Jeffery!
The Jeffery case give birth to an amazing number of now-famous offspring, as it is the parent case for the Remington Ultra Magnum series, as well as the Winchester Short Magnum and Dakota Magnum series.
Source: Philip P. Massaro
450 Rigby left, 308 Win. right
The .450 Rigby is actually a relatively new cartridge, launched by Rigby in 1995, almost 100 years after the introduction of the famous .450 Nitro Express.
It was an elephant hunt by Paul Roberts, the owner of Rigby, which led to the development of this cartridge. He landed a well-placed lung shot with a .416 Rigby, and the elephant cow moved on a considerable distance with several more shots. Disappointed with the performance of his round, he concluded that extra weight and bullet diameter would be beneficial for taming the earth's largest land animal.
Wolfgang Romey took the challenge and necked up the Rigby case to .458". Given that Rigby already manufactured many rifles for the highly regarded .416, simply necking up this cartridge required minimal additional manufacturing expense or design development.
The new cartridge is able to push a 500-grain bullet with moderate chamber pressure of 55,100 Psi, at 2,400 fps, generating 6,400 ft-lbs muzzle energy. With a sectional density of .341 and a KO value of 78, this caliber will perform extremely well in a professional hand.
The downside is that the cartridge also needs a magnum-length action and a non-standard magazine to fit the fat case. Powder consumption is also a considerably due to the large case capacity. For normal loads the .450 pushes back with approximately 80 to 90 ft-lbs of recoil energy. For comparison, the recoil of a .243 Win will be around 9 ft-lbs.
Nevertheless, the .450 Rigby is surprisingly manageable compared to some of the other big cartridges, which kick you abruptly with head-snatching violence. It can be described more like a hard push. However, the 450 Rigby is already more a PH caliber instead being a universal African client one.
For the pure elephant hunter it can be an excellent tool like the .500s, if properly managed.
The .500 Jeffery or 12,5 x 70 Schueler was probably developed somewhere around 1904. At that time, Richard Schueler applied for a patent, describing cartridges with a smaller rim diameter than case diameter. Around 1927 the British gun maker Jeffery started to use the cartridge. Unfortunately, the new caliber did not become a big success as the main ivory & elephant hunting era was over. Jeffery only produced 23 bolt-action rifles in that particular caliber.
One of the big advantages of the .500 Jeffery is that the cartridge fits still in a standard 98 Mauser System. The short case of only 2.75" and the overall length of 3.46" makes it possible. Additionally, the smaller rim diameter allows the fitting in a standard Mauser 98 bolt head.
The .500 Jeffery is loaded with 535-grain bullets but 600-grainers are also available. The 535-grain bullet accelerates up to 2,300 fps, generating a muzzle energy of 6,285 ft-lbs. It was the strongest standardized bolt-action cartridge of that time and it is still an impressive one.
Norbert Klups wrote:
"You should know what you are doing and which forces you will release by firing the .500 Jeffery. The .500 Jeffery develops a recoil energy of nearly 100 ft-lbs with the tested rifle. For comparison, an approximately 10 pound rifle in .416 Rigby will develop a recoil of just 41 ft-lbs."
The .500 Jeffery has a sectional density of .330 and a KO Value of 92 (600-grain bullet), which makes it interesting as back-up cartridge for professional hunters. However, it is certainly too much for an all-round client rifle.
John A. Hunter was one of the most famous "White Hunter" in East Africa. As a professional hunter, he hunted more than 1,500 elephants and his preferred rifles was a Mauser 98 in .505 Gibbs.
George Gibbs developed the .505 Gibbs in Bristol, England. Originally, he wanted to develop a rimmed cartridge but changed his mind and presented 1914 the rimless .505 Gibbs for Mauser Magnum Systems. Gibbs himself only produced 52 bolt-action rifles in that particular caliber.
Hunter said about the .505 Gibbs: "There is nothing comparable that will stop an elephant better than the .505 Gibbs". John "Pondoro" Taylor wrote in his book "African Rifles and Cartridges", that he was surprise by the mild recoil of the .505 Gibbs. It was pleasant to shoot from a Mauser bolt-action rifle and the accuracy was excellent. For use on dangerous and thick-skinned game, the cartridge is a perfect choice.
The .505 Gibbs has a case length of 3.15" and a rim diameter of 0.64". Therefore, it needs the Mauser Magnum System, which is sufficient long and has the bigger bold-head. The .505 Gibbs has compared to the .500 Jeffery the same rim diameter as case diameter. That is reducing the risk of feeding issues. The maximum chamber pressure is only 39,160 Psi.
The 3.85" long cartridge is normally loaded with 535-grain bullets but also 600-grain bullets are available. The bullet diameter is .505" (12.83 mm) and with the 600-grain bullet, the muzzle velocity is 2,100 fps. This impressive combination is generating a muzzle energy of 5,873 ft-lbs.
The .505 Gibbs is certainly a cartridge for thick-skinned game but can also be used for Lion or Eland. With a sectional density of .336 and a KO value of 91 it is a bit too much for the other African game e.g. plains game.
It is the favorite cartridge of Kevin Robertson (The Most Dangerous).
Source: Roland Zeitler