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, which should be taken into account for the caliber decision as well as the ammo ordered for your double.

This list is not exhaustive. 

Three figures that can help to understand the ballistics of a certain Cartridge:

Sectional Density

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.

KO Value

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. Taylor's KO value is 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 expant 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 Flanged

Left side 375 H&H Flanged, Right side 308 Win.

The .375 Holland & Holland Flanged Magnum is a medium-bore rifle cartridges as its belted version for bolt-actions .375 Holland & Holland Magnum. 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. Therefore, I would recommend for large and dangerous game one of the 40th calibers with a higher KO Value.

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 shooting. Especially, an unknown wounded buffalo can be a risk for life.

450/400 3" & 3 1/4" N.E.

450/400 3 1/4" left, 450/400 "3 middle, 308 Win. right 

Left: 500/416 N.E., Middle: 450/400 3"1/4 N.E., Right: 9,3x74R

The original 450/400 3¼" cartridge was not strong enough for the pressures of the early Cordite loadings and therefore, had the tendency to stick in the chamber of rifles. The British Gunmaker W.J. Jeffrey designed a new version of the 450/400 in 1902 which he called the 400 Jeffrey Nitro Express: other Gunmakers also began using Jeffrey's new design and called it the 450/400 3″ Nitro Express.

The 450/400 Nitro Express is based on a straight sided 450 caliber parent cartridge necked down to take a smaller diameter projectile in a bottle-necked case. The bullet diameter is 0.411 inches. Regular bullet weight is 400 grains, but 350s can also be found. Normal velocity with the 400-grain bullet is about 2100 feet per second and produces around 3918 ft-lbs of muzzle energy.

The beauty of the .450/400 N.E is that it has the mildest recoil of all the valid dangerous game cartridges. Many shooters find the .450/400 even easier to shoot than the .375 H&H. With a sectional density of .338 and KO value of 47 it will give excellent penetration, making it a perfectly viable cartridge, even for elephant.

In his African Rifles and Cartridges, John "Pondoro" Taylor stated the 3-inch and 3¼-inch .450/400 NE cartridges to be "the grandest weapons imaginable for all big game hunting" adequate for all African game in almost all conditions when used by an experienced hunter. He further stated "I derived greater pleasure from using the .400 than any other calibre; and no weapon behaved more successfully in my hands. I would happily finish the remainder of my career with a pair of them and nothing else-unless it was a third!

(John Taylor, African rifles and cartridges, Sportsman's Vintage Press, 2013, ISBN 978-1-940001-01-2)

500/416 N.E.

The Case can be re-formed from a 500 N.E. 3 1/4" or a 470 N.E.

500/416 N.E. left, 308 Win. right

The reputation and performance of the .416 Rigby is undeniable and because there are double rifles chambered to these cartridges, Krieghoff saw the wisdom of a rimmed cartridge using a .416" diameter bullet. Early in 1996, Krieghoff unveiled the .500/.416 Nitro Express 3 ¼", based on the proven .500 3 1/4" Nitro Express case, with a nice, long neck for good bullet tension, a good taper for easy feeding under duress, and enough case capacity to mimic the performance of the rimless .416s. The result was a winner - the .500/.416 NE pushes a 410-grain bullet at 2,325 fps, for just under 5,000 ft.-lbs. of energy at the muzzle. This ballistic formula has been used on the largest game on earth with great results. It will also allow the reliable, immediate second shot that double rifle shooters have come to appreciate.

The 500/416 N.E. offers a heavier bullet weight - 400 grains - than the .375. It offers less muzzle jump than does the .450 NE or the .470 NE, which allows the shooter to get back on target quicker for a much faster second shot, an important feature when it comes to dangerous game. The .500/.416 N.E. bridges a huge gap between the .450/400 and the .450 NE, and offers a shooting experience closer to the .450/400, while giving plenty of power for hunting any dangerous game.

When comparing the two, 450/400 3" and 500/416 N.E., the .500/.416 offers a bit more frontal diameter (.416" v. .411") and a considerable increase in velocity (2,350 vs. 2,150, depending on manufacturer), so it boils down to whether you desire a bit more reach-out-and-touch or the lesser recoil of the lighter cartridge. The .500/.416 NE is a double rifle cartridge with a performance level on par with the highly familiar .416 Rigby.

A pair of 400-grain Woodleigh bullets - a soft point and a solid for the classic 'right-and-a-left' - has a high Sectional Density figure of 0.330, and will deliver the excellent performance.

Source: Norma-USA

The .450 Nitro Express cartridges

Dimension of the other two can be found in wikipedia.

Left 450 No. 2 NE (3 ½), Middle 500/450 3 ¼ NE, Right 450 3 ¼ NE

450 3 ¼ Nitro Express

John Rigby & Co. introduced the cartridge, in 1898. The cartridge was based on the 450 3 ¼ Black Powder Express which was already available before 1871 and was used by Selous and Taylor for elephant hunting. For many years, it was considered the standard elephant or dangerous-game cartridge and enjoyed great popularity. Early cartridges used the black powder case that was designed for lighter breech pressure and not for the stronger Cordite loads. Case extraction was difficult, especially in warmer climates such as Africa and India where the cartridge was primarily used. These initial problems led to the development of the Holland & Holland .500/450 Nitro Express and Eley's .450 No. 2 Nitro Express. Both offers very similar performance to the original .450 3 ¼ Nitro Express. Better brass quality and thicker case walls, later solved the initial problems of the cartridge. These cartridges propel a 480-grain bullet of .458- inch diameter to a speed of approximately 2,150 fps and generate around 5,000 ft.-lbs. of muzzle energy.

The .450 3 ¼ Nitro Express is considered adequate for dangerous African game or any other game. It would most likely have been the only British cartridge used for big-game hunting, if the British law had not banned the import of .45-caliber rifles or cartridges into India and Sudan. Nevertheless, the .450 3 ¼ Nitro Express was, and is still, a winner, and many double-barrel rifles for this cartridge are still in service.

.450 No. 2 Nitro Express (3 ½ inch)

This cartridge uses a longer case than the .450 3 ¼ Nitro Express, but has the same bullet weight, loaded to the same velocity. It was introduced about 1900-1902 by Eley. It has a thick rim to aid extraction and the longer case is working with lower breech pressure. The cartridge was later opened up to become the .475 No. 2 for importation into India and Sudan. Many rifles in this chambering are still around.

500/450 3 ¼ Nitro Express

The 500/450 3 ¼ NE. is a rimmed cartridge which, was introduced probably by Holland & Holland around the turn of the century. It is based on the black powder cartridge .500/450 Magnum Express which, was originated somewhere around 1870. It is usually loaded with 480-grain soft-point or solid bullets, but other slightly lighter loadings sometimes appear. It is a fine performer. Theodore Roosevelt had a double-barrel rifle in this chambering. Holland & Holland opened this up to become the .500/465 Nitro Express. after the ban on .450-bore rifles in India and Sudan.

As the .450 No. 2, the cartridge was a primer competitor of the .450 3 ¼ inch NE. Performance of the three is practically identical. All three cartridges have about the same killing power, and the choice becomes more or less a matter of individual preference. All three are large cartridges that develop quite low pressures and are therefore suitable for hot climates. 

Two modern rimmed 450's are the .450 Assegai from A-Square and the .450 KNR developed in 1992 by Kase Reeder. The .450 KNR propels a .458-inch, 500-grain bullet to a speed of approximately 2,300 fps and generate around 5,872 ft.-lbs. of muzzle energy. As it is in principle a necked down 470 N.E., it is an interesting option for hunters who hand load ammunition.

470 N.E.

470 N.E. left, 308 Win. right 

The 470 N.E. was introduced in 1900 by Grant and Lang and became one of the most popular Nitro Express cartridges for dangerous game in Africa. It is based on the .500 Nitro Express 3 ¼" case, necked down to hold bullets that are .475" in diameter. The Nitro Express era started in 1898 with the introduction of the .450 NE from John Rigby. In 1907, the British government banned the .450 in India and Sudan, where tribal riots were taking place. The .450 bullets could also be reloaded for use in the existing Martini/Henry rifles. This ban of the popular 450's was a push for the legal to use 470 N.E.

The performance of the 470 N.E. is nearly par with the modern .458 Winchester but uses approximately 35% less chamber pressure. Driving a 500-grain round nosed bullet to a muzzle velocity of 2,150 fps, the .470 Nitro Express generates 4,897 ft.-lbs. of muzzle energy.

It is definitely not a long-range cartridge; when zeroed for 100 yards, the 500-grain Woodleigh bullet will drop nearly 4 inches at 150 yards. However, most animals hunted with that cartridge are shot closer than 100 yards.

The recoil of 72 ft-lbs with an 11 pound rifle, is already a solid hit for the shooter. Unlike some of the huge-cased overbore magnums, the recoil is still more of a classic 'push', but far from being soft. A double rifle of sufficient weight will help to tame some of that recoil, and let the shooter get back on target for the second shot.

With its sectional density of .317 and a KO value of 73 it scratch already the PH-Back-up-Rifle category and needs good training to shoot it sustainable good. 

500 N.E. 3"

Source Private: Mr. Renz

The old .500 Express was simply equipped with a new propellant; "Cordite" and was renamed to Nitro Express as the era of black powder run out. The caliber was available in two different 500 Nitro Express cartridges. The 3" and the 3 ¼" version. Both have a nearly identical performance but the 3 ¼" is doing the job with a bit less of chamber pressure. The bullet diameter is .510 in in both cartridge version.

The performance of that cartridge is impressive. It is firing a 570 Grain bullet at 2,100 fps, ending up in 5,538 ft.-lb. muzzle energy with a chamber pressure of only 2,500 bar. It has a sectional density of .313 and a KO value of 89, which is enough performance for any living species on earth. Nevertheless, it is not considered too powerful for the use against big cats. Using bullets capable of expanding quickly such as the 570 gr A-Square Lion Load.

The bullet will drop nearly 4 in at 150 yards when zeroed at 100 yards. When firing it generates a recoil of 76, ft-lbs compared to the 72 ft-lbs of the 470 N.E. Both cartridges will need constant training and a shooter not too sensitive to recoil.

The 500 N.E. can have issues when it comes to shots where deep penetration is mandatory e.g., a slightly sided frontal head shot to an elephant. In that case, the bullet has to penetrate the thick muscle base of the elephants trunk, the strong tusk base and the full length of the Skull to reach the brain. Except of such exceptional situations the 500 N.E. is a powerful tool in an experienced hand.

The 600 N.E. and the 700 N.E. are not listed by purpose. The weight of rifles and the recoil of both cartridges are in most cases a bit to much for the average hunter.