Compared: Medium Bore Magnum Rifle Cartridges
By Chuck Hawks
This article is a comparison of the best known medium bore magnum rifle cartridges. Factory loaded ammunition is available in mainstream brands for all of these calibers. The cartridges included in this article are all more or less based on the .375 H&H case with a rim diameter of .532" and a head diameter no greater than .532"
There are even larger medium bore magnum cartridges based on necked-down elephant rifle cartridge cases (.404 Jeffery, .416 Rigby, etc.), but they are not included here. Truthfully, the "normal" medium bore magnums compared here can do everything--and then some--that a medium bore rifle can reasonably be expected to do. If you think that you need more killing power than is provided by the cartridges below, you need a big bore rifle cartridge.
The medium bore magnums kick too hard to appeal to most shooters and hunters. There are, however, legitimate applications for such cartridges when hunting the largest or most dangerous North American game, including moose, the great bears and bison, as well as similar size game around the world. The medium bore magnums have been especially popular for hunting the largest plains game in Africa, including lion and Cape buffalo, as well as (when legal) for hunting tiger and water buffalo in Asia and elsewhere.
These are romantic cartridges that evoke images from the past of brown bear hunts on Kodiak Island, lions in the tall grass in Kenya, and tiger in the Indian jungle. One thing is for certain; the medium bore calibers have always gotten far more ink in the sporting press than their sales would seem to warrant. The result has been to keep interest in medium bore cartridges at a high level, even among shooters who have no real need for such calibers (and, admittedly, most don't).
.338 Winchester Magnum
The .338 Win. Mag. is by far the most popular of all medium bore cartridges, and the only medium bore on the list of "top 10" best selling centerfire rifle cartridges. It was designed primarily for use on the heaviest Alaskan game, and the Winchester Model 70 rifle in which the .338 Mag. was originally introduced back in 1958 was named the "Alaskan." The name was fitting, and the .338 has gone on to become the most popular of all cartridges with Alaskan big game guides who need a powerful rifle to "back up" their clients.
The .338 Win. Mag. is based on a necked-down .375 H&H case shortened to work in rifles with standard (.30-06) length actions and blown out to maximize powder capacity. The result is a cartridge with penetration and killing power close to that of the .375 H&H and less recoil than the larger medium bore cartridges.
Depending on the bullet weight and load chosen the .338 Win. Mag. can shoot as flat as a .300 Magnum or penetrate heavy game as well as a .375 Magnum. The load that has really made the .338's reputation as a slayer of heavy game all around the world is a 250 grain bullet at a MV of about 2660 fps, and loads along those lines are offered by most major ammo manufacturers. Federal, for example, loads the 250 grain Nosler Partition spitzer bullet to exactly that velocity, and that is one of the .338 Win. Mag. loads that we will use in this comparison. The other is the Winchester offering using a 225 grain Nosler AccuBond bullet at a MV of 2800 fps, which is a fine long range and general purpose load.
.340 Weatherby Magnum
The success of the .338 Win. Mag. begot a number of other .338 caliber cartridges, among which the best known is probably the .340 Weatherby. Despite its unusual name, the .340 actually shoots the same .338" diameter bullets as the .338 Magnums.
The .340 Weatherby is based on the full length .375 H&H case necked-down and blown out to increase powder capacity. It is a very powerful and flat shooting cartridge, sort of a .338 Win. Mag. on steroids. Naturally, its recoil is also proportionally greater. The .340 is not fun to shoot.
As with any .338 caliber magnum, a 250 grain bullet is the best choice for use on very large game. Weatherby factory loads drive a 250 grain Nosler Partition spitzer bullet at a MV of 2941 fps, which is the load that we will compare in this article.
.358 Norma Magnum
The .358 Norma Magnum is based on the .338 Win. Mag. necked-up to accept .358" diameter bullets. This results in a similar cartridge that gains in the area of bullet frontal area at the expense of sectional density. Norma factory loads launch a 250 grain Swift A-Frame bullet at a MV of 2723 fps.
Although it has been around since 1959, the .358 Mag. has a reputation as a hard kicker and has never really caught on with the buying public. It remains available, however, and has proven to be an effective heavy game cartridge.
This is the newest of the medium bore magnums as of this writing. It was introduced in 2007 and is designed to deliver .375 H&H performance from a case that will work in standard (.30-06) length actions. It is based on a new case that is basically a shortened .375 H&H Mag. case with its belt removed.
Hornady designed the cartridge for Ruger and loads factory ammunition in the caliber. The only spitzer bullet offered is a 270 grain Spire Point at a MV of 2840 fps. Note that this load is based on non-canister powders and cannot be duplicated by reloaders. The other Hornady factory loads use 300 grain round nose soft point and FMJ bullets at a MV of 2660 fps. A 300 grain bullet has traditionally been the most popular weight in the .375 Magnums, but in the .375 Ruger the 270 grain spitzer bullet would seem to be the more desirable projectile for all but CXP4 class game, so that is the load that we will compare here.
.375 Holland & Holland Magnum
The late Jack O'Connor, Dean of American gun writers, described the .375 as the Queen of the medium bores. It was one of his favorite cartridges because it combined the power to harvest any land animal on earth with the relatively flat trajectory of the common .30-06/180 grain load and recoil that an expert like O'Connor could tolerate.
Holland & Holland introduced their .375 in 1912 on a long, belted case with a rim diameter of .532", and that has remained the standard rim diameter for magnum cartridges to this day. Holland's big 2.85" long .375 belted case became the starting point for the majority of subsequent magnum cartridges, including all of the other medium bore cartridges covered in this article.
.375 H&H ammunition is offered by most of the world's big ammunition manufacturers. The most enduring .375 loads have used 270 and 300 grain bullets. Hornady offers a Heavy Magnum load for the .375 that launches a 270 grain Spire Point bullet at a MV of 2870 fps and Federal Cartridge loads the 300 grain Nosler Partition spitzer bullet to a typical MV of 2530 fps. Those are the two .375 H&H factory loads that we shall use for this comparison.
.375 Weatherby Magnum
The .375 H&H case has plenty of body taper and a mild shoulder angle to accommodate the long strand Cordite powder in use when it was designed. A number of wildcatters have taken the full length .375 case and "Improved" it by blowing it out (fire forming) to sharpen the shoulder and increase powder capacity. Among these was the inimitable Roy Weatherby, whose .375 Magnum Improved reached commercial cartridge status as the .375 Weatherby Magnum.
The .375 Wby. Mag. became the most popular, and perhaps the best, of the .375 H&H Improved cartridges. It differs from the original .375 H&H by having minimal body taper and a sharp double radius shoulder. One of the nice things about it is that, in a pinch, standard .375 H&H cartridges can be fired in a .375 Weatherby rifle. .375 Weatherby factory loads launch a 300 grain Nosler Partition spitzer bullet at a MV of 2800 fps. This extremely potent load, unfortunately, makes the .375 even less fun to shoot than the .340 Weatherby Magnum.
We will compare the ballistic coefficient (BC), sectional density (SD), velocity, energy, trajectory, bullet frontal area, killing power, and recoil of our representative medium bore magnum factory loads. We will also touch on the availability of rifles and ammunition in these calibers. At the end we will summarize what we have learned and, maybe, reach some conclusions.
Ballistic Coefficient and Sectional Density
Ballistic Coefficient is a measure of a bullet's ability to fly through the air. The higher the BC number, the less air drag. BC matters because the bullet with a higher BC will evidence less drop and also less wind drift over any given range, other factors being equal.
The sectional density of a bullet is calculated by dividing the bullet's weight (in pounds) by the square of its diameter (in inches). Sectional density is important because, if all other factors are equal, the bullet with the greatest SD will penetrate the deepest. A crude example would be that at the same velocity a needle (a long and slender shape) penetrates better than a round ball (a short, fat shape) of the same weight. The deeper the wound channel (of any given diameter) in a game animal the more tissue is destroyed and the greater the killing power. Penetration is especially important when comparing cartridges designed for hunting large and possibly dangerous game, as great penetration is often required to reach the vitals.
Here are the BC and SD numbers for the various bullets used in our comparison loads.
Note that the .338/225 grain bullet has a slightly superior SD to the 250 grain .358 bullet and the 270 grain .375 bullet. Also, the 250 grain .338 bullet is superior in SD to the 300 grain .375 bullet. This bodes well for the .338 Magnums' penetration.
Higher velocity means flatter trajectory, given bullets of equal ballistic coefficient (BC). Velocity is also the most important component in the formula used to compute kinetic energy. Here are the velocity figures for our various factory loads (in feet per second) from the muzzle (MV) to 300 yards.
The Weatherby calibers, and to a lessor extent the .338 Win. Mag., offer higher velocity than the others Magnums at the longer ranges. We will soon see how this effects subsequent results.
Kinetic energy is defined as the ability to do work. The "work" in this case is powering bullet expansion and penetration to create the largest possible wound cavity.
Energy is an important factor in killing power and it is commonly used to compare the power of rifle cartridges. Practically all factory ballistics tables show both velocity and energy figures. Here are the energy figures (in foot pounds) for our selected loads from the muzzle (ME), to 300 yards.
All of these cartridges produce plenty of energy at all ranges. That is a product of decent velocity and heavy bullets. The Weatherby cartridges, due to their superior velocity, deliver the most energy downrange. Speed kills.
Among the other cartridges, the .338 Win. Mag. with both 225 and 250 grain bullets makes a surprising showing. Trailing all of the other cartridges in muzzle energy, it has surpassed the .358 Norma by 100 yards, and the .375 H&H/300 by 300 yards. That is a tribute to the higher BC of its relatively long, slender bullets. For the long range elk and moose hunter, the .338 Win. Mag. will outperform the fatter .358 and .375 caliber cartridges. (Also note the trajectory results in the next section.)
Trajectory is important because the flatter a bullet shoots the easier it is to place it accurately downrange. And bullet placement is the most important factor in achieving quick, clean kills with any hunting rifle. Here are the published trajectory figures for our selected loads predicated on a 200 yard zero when fired from rifles with a scope mounted 1.5" over the line of bore. Trajectory is given in inches above or below the line of sight at 100, 200, and 300 yards.
The .340 Weatherby shoots noticeably flatter than the other calibers. If a flat shooting medium bore magnum is especially important to your needs, that is the caliber of choice. The .338 Win. Mag. 225 grain load is also a flat shooting number, worthy of consideration for long range big game hunting.
Actually, all of these cartridges shoot commendably flat, even with heavy bullets. Their trajectories are quite comparable to that of the standard Federal .30-06/180 grain Nosler Partition factory load. That cartridge shows a drop of -8.6" at 300 yards.
Bullet Cross-Sectional Area
Bullet cross-sectional area (frontal area) is important because, when comparing two bullets of equal construction, SD, and expansion ratios but different diameters, the fatter bullet will make a wider wound channel, thus destroying more tissue in the game animal. The actual diameter of .338 Win. and .340 Wby. bullets is .338", the actual diameter of .358 Norma bullets is .358", and the actual diameter of .375 Magnum bullets is .375". Here are the cross-sectional areas (in square inches) of our three calibers.
Obviously, the .375 bullets have the most frontal area, and the .338 bullets have the least. In terms of wound channel area, frontal area (a wider wound cavity) tends to be off-set by sectional density (a longer wound cavity).
OGW Killing Power
Killing power is the hardest of all factors to quantify, and all attempts to do so must be approximations. We know that energy, penetration, and bullet frontal area (among others) are important factors in killing power, but not exactly what is the best blend of these factors.
Optimum Game Weight (OGW) is a system intended to express the killing power of rifle cartridges in terms of an animal's live weight and the optimum distance at which it should be taken with a given cartridge and load. Thus it compares the killing power of different cartridges and loads in a way that is relevant in the field. Edward A. Matunas devised the formula used to determine the OGW for which rifle cartridges are suitable at various ranges. This system assumes bullets designed for adequate penetration and expansion for their intended application.
The OGW formula is not perfect, but when used to compare similar rifle cartridges, as we are doing, it seems to have a positive correlation with reality. Here are the OGW figures (in pounds) for our selected loads at the muzzle, 100, 200, and 300 yards.
In killing power the high velocity/energy of the Weatherby calibers moves them to the top of our list at most ranges. The average adult lion weighs about 350 pounds, average Rocky Mt. bull elk about 500 pounds, North American bull moose about 600-1000 pounds, adult male grizzly/brown bear about 700 pounds, polar bear about 900 pounds, Cape buffalo about 1000 pounds, and the average adult male American bison or Asian water buffalo about 1600 pounds.
When you consider that dangerous game is rarely shot at distances greater than 100 yards, where the OGW of the "lightest" of our calibers is still over 1400 pounds with the heaviest bullet, and you can see that all of these medium bore magnum cartridges have excellent killing power. As a point of fact, all of these calibers except the new .375 Ruger have been around long enough to have proven reliable (with proper bullet placement) on all of the animals mentioned in the paragraph above. (Use the heaviest bullets for maximum penetration on the bovines.) With proper, usually solid, bullets the .338/250 and .375/300 loads have also proven up to the task of harvesting even rhino and African elephant.
When you are talking about cartridges capable of blasting huge beasts into oblivion, there is a price to be paid beyond the monetary cost of rifles and ammunition. That price is recoil, the arch enemy of accurate bullet placement. And, bullet placement is the most important factor in killing power. Always consider recoil when planning the purchase of a new hunting rifle, particularly a medium bore magnum rifle.
Heavy recoil promotes flinching, which is the leading cause of those embarrassing missed shots at big game animals. Here are some approximate recoil energy (in foot pounds) and velocity (in fps) figures for our selected loads when fired in 9 pound rifles.
Those are punishing recoil numbers. And remember that many rifles chambered for these calibers will weight less than 9 pounds with a scope and mount. Lower weight will significantly increase recoil. Consider that approximately 15 ft. lbs. of recoil energy is about the maximum comfortable level for most shooters, and 20 ft. lbs. is the most they can endure without developing a flinch, and you see the problem with the medium bore magnums.
Still, there are differences. The .338 Win. Mag. and .358 Norma Mag. are the most tolerable of our calibers. This probably helps to explain the popularity of the .338 Win. Mag. The .375 H&H 300 grain load represents the next level of recoil, noticeably more than the .338 Mag, but also noticeably less than the .375 Ruger and the .340 Weatherby Magnum. Alone at the top of our recoil list is the .375 Wby. Mag., which would make a wooden Indian flinch. Unless you are very experienced at dealing with extreme recoil it would be wise to limit consideration to the .338 Win., .358 Norma and .375 H&H if you are shopping for a medium bore magnum rifle.
Availability of Rifles and Ammunition
Only one of these calibers is genuinely popular, and that is the .338 Winchester Magnum. It is available in a variety of types and brands of rifles and almost all major manufacturers load ammunition. .338 factory loads offer many choices of bullet styles and weights, and reloaders are blessed with even more bullet choices.
In second place in sales among our list of medium bore magnums is the .375 H&H Magnum. The H&H wonder cartridge is available around the world and is particularly popular in sub-Saharan Africa where, due to archaic game laws, it is often considered the minimum cartridge legal for hunting Cape buffalo, rhino, and elephant. Most major ammo companies load 270 and 300 grain bullets for the .375 H&H, and there is a reasonable selection of bolt action rifles for hunters and bullets for reloaders.
The other calibers are rather poorly represented in both factory loaded ammunition and available rifles. There may be only one brand of each offered. Brass for reloading may be hard to come by as well as expensive. In this very important category the .338 Win. Mag. has a big advantage, the .375 H&H a significant advantage, and the other four calibers are at a disadvantage.
The .358 Norma, .375 Ruger, .340 Weatherby and .375 Weatherby are truly limited in terms of available rifles. Weatherby ammunition for their .340 and .375 is probably the most widely distributed of these four calibers. Far better for the traveling hunter are the .338 Win. Mag. and .375 H&H Mag. These calibers are well known wherever large and dangerous game is hunted and ammunition and reasonably priced production rifles are widely available.
Summary and Conclusion
The .340 Wby. is the flattest shooting of our medium bores. It is the best long range cartridge of the bunch if you can stand its considerable recoil. In second place as a long range cartridge would be the .338 Win. Mag., as it can handle lighter 225 and 200 grain bullets of respectable ballistic coefficient for long range work. This added versatility is an advantage of both of our .338 calibers. They are in the same general class as long range calibers as the common .300 Magnums with 180 grain bullets.
In terms of ballistics and raw power, the .340 and .375 Weatherby cartridges are the winners. They are also at or near the top in sectional density, since their big cases with long necks can easily handle the heaviest bullets in their respective calibers. They don't do so well in cartridge and rifle availability, although Weatherby rifles and cartridges are generally available worldwide if you look for them. The .340 and .375 Weatherby are probably ahead of the .358 Norma and .375 Ruger in terms of availability, but well behind the .338 Win. and .375 H&H.
The .358 Norma is a fine but obscure caliber that has been around for decades. It delivers killing power much like the more moderate .375 H&H loads, but is hampered when compared to the .338 and .375 calibers by the lack of a bullet with a SD in excess of .300 for maximum penetration on CXP4 class game. Ammo and rifles in the caliber are also extremely scarce, and that situation is unlikely to improve in the future.
The .375 Ruger is the ballistic twin of the .375 H&H in a standard length cartridge, as it was designed to be. It scores well in every category except recoil and availability. The latter will likely improve in the future if the cartridge catches on. Right now it is too soon to know for sure what the future holds for the .375 Ruger.
The .375 H&H, due to its long and imposing case, looks much more powerful than the .338 Win., .358 Norma and .375 Ruger. However, with the hottest available loads it merely equals the .375 Ruger and with standard loads it is not dramatically superior in killing power to the .338 and .358, which are .30-06 length cartridges. The most significant advantage enjoyed by the .375 H&H is due more to its history than anything else, namely its acceptance as a heavy and dangerous game cartridge around the world. It remains probably the best medium bore cartridge to take to Africa.
The .338 Win. Mag. scored well in BC, SD, trajectory, (less) recoil, and availability of rifles and ammunition. It shoots flatter than the .375 H&H, kicks less, and kills almost as well. It is adequate for all North American game and for similar size game anywhere in the world. (Note, however, that some African countries have laws restricting caliber for the biggest animals to .375 or larger.) Especially for North American hunters, the .338 Win. Mag. is the odds-on favorite among all medium bore calibers.
Copyright 2007, 2012 by Chuck Hawks. All rights reserved.