Compared: 7mm WSM and 7mm Remington Magnum
By Chuck Hawks
The 7mm Remington Magnum is the most popular of all magnum cartridges. The 7mm WSM (Winchester Short Magnum) is a short action cartridge intended to equal 7mm Rem. Mag. ballistics with bullets weighing up to 160 grains. Since Winchester has taken direct aim at the world's best selling 7mm Magnum cartridge with the new 7mm WSM, a comparison seems inevitable.
Since the published ballistics of the two cartridges are so similar, and they can be loaded with identical bullets, there is little point to an extensive ballistic comparison. This article will look primarily at other differences between the new 7mm WSM and established 7mm Rem. Mag.
The 7mm Remington Magnum
The 7mm Remington Magnum was introduced in 1962, and took the market by storm. For a long time rifles for the new cartridge were in short supply, as every one that Remington could produce was immediately snapped-up by an eager buying public. The 7mm Rem. Mag. was designed for use in standard (.30-06) length actions such as the Remington Model 700. It was quickly adapted to the Winchester Model 70, Savage 110, and a plethora of other popular rifles.
The 7mm Rem. Mag. is based on the .338 Win. Mag. necked down to accept 7mm (.284") bullets. This is a standard belted case with a rim diameter of .532", scant body taper, a sharp 25 degree shoulder, and a short .2712" neck.
The purpose of this design is to maximize powder capacity, allowing the 7mm Rem. Mag. to outperform most other standard length 7mm Magnum cartridges and nearly equal the performance of the class leading 7mm Weatherby Magnum. The weakest point of the design is the short neck of less than one caliber length, but it has proven satisfactory in service.
The Winchester Supreme factory loads for the 7mm Rem. Mag. drive a 140 grain bullet at a MV of 3150 fps, a 150 grain bullet at a MV of 3130 fps, and a 160 grain bullet at a MV of 2950 fps. Remington offers similar loads, plus a 175 grain bullet at a MV of 2860 fps. Hornady Heavy Magnum factory loads offer a choice of 139 grain bullets at a MV of 3250 fps. These are representative of 7mm Rem. Mag. factory loads, although virtually every ammunition maker loads for the caliber.
Factory ballistics for the 7mm Rem. Mag. are achieved in 24" test barrels, and most hunting rifles in the caliber come with 24" barrels, so the advertised ballistics usually check out reasonably well when chronographed in hunting rifles.
For more information about Remington's Big 7, please see my article "The 7mm Remington Magnum" on the Rifle Cartridge Page.
The 7mm WSM
Winchester based their 7mm Short Magnum on a necked-down version of the previous .300 WSM case, itself based on the .404 Jeffery case drastically shortened to a case length of 2.1" and a COL of 2.860". The 7mm WSM has a rebated rim that will match up to a standard magnum diameter bolt face. It has a very sharp 35 degree shoulder, which is set slightly farther forward than the shoulder of the .270 WSM case to prevent dangerous accidents. The case neck is considerably less than one bullet diameter, at only .243" long. The result of these design trade-offs (sharper shoulder, very short neck, and fat case with rebated rim) is that the 7mm WSM has a similar powder capacity to the 7mm Rem. Mag. case.
For technical reasons fat, short, rebated rim cartridges with very sharp shoulders tend to cause feeding problems from the box magazines typically found in bolt action (and other types of repeating) rifles. This may be why Winchester offers the 7mm WSM only in controlled round feed models of their Model 70 rifle. Savage 110's and Browning A-Bolt II's, however, are push feed rifles and they are also available in 7mm WSM caliber.
I have received reports from the field of feeding problems with WSM rifles. While these reports are not so frequent that I would necessarily advise against purchasing a 7mm WSM rifle, it is something to keep in mind. It is clear that 7mm WSM rifles are not as reliable as 7mm Rem. Mag. rifles because of this problem.
Winchester factory loads for the 7mm WSM come with 140, 150, and 160 grain bullets. The 140 grain Ballistic Silvertip bullet has a catalog muzzle velocity (MV) of 3225 fps. The 150 grain Power Point bullet has a catalog MV's of 3200 fps. The 160 grain Fail Safe bullet has a MV of 2990 fps. As far as I know, no other ammunition company offers 7mm WSM factory loads. Winchester 7mm WSM data was developed in 24" test barrels.
Winchester wisely provides 24" barrels on all 7mm WSM caliber rifles. Browning, however, has standardized the somewhat unusual length of 23" for their 7mm WSM rifle barrels. The velocity loss in these shorter barrels should amount to about 30 fps, according to Remington estimates. For more information about the 7mm WSM please see my article "The 7mm WSM" on the Rifle Cartridge Page.
The 7mm WSM was designed to give 7mm Rem. Mag. performance in a short action rifle with bullets of 140-160 grains and, as we have seen above, it does just that. There is very little difference between the ballistics of the two calibers as factory loaded.
The difference is in the variety of factory loads available. The 7mm Rem. Mag. is a worldwide hunting cartridge and practically all ammunition manufacturers load for the caliber. The 2004 edition of the Shooter's Bible, for example, lists 54 different factory loads for the 7mm Rem. Mag., in bullet weights of 139, 140, 150, 154, 160, 162, 165, 170 and 175 grains. And those are just the loads commonly encountered in the U.S. They do not include many loads available from European, African and Australian cartridge manufacturers.
The same Shooter's Bible lists exactly 3 factory loads for the 7mm WSM, in bullet weights of 140, 150 and 160 grains (1 each). The hunter who relies on shooting factory loads could quickly run into trouble if his particular rifle did not provide its best performance with one of those bullet weights or loads.
Clearly, the hunter who shoots a lot of factory loads would do well to choose the 7mm Rem. Mag. So would the hunter who is planning to hunt on a continent other than North America, as I know of no 7mm WSM ammunition being loaded overseas.
There are plenty of bullet choices for any 7mm (.284) caliber rifle, and the selection is the same for the 7mm Rem. Mag. or the 7mm WSM. The situation is much the same for powders, and both calibers use large rifle magnum primers.
The sixth edition of the Hornady Handbook of Cartridge Reloading shows virtually identical velocities with maximum powder charges behind all bullet weights (100-175 grains) in the two calibers. The test rifles for both calibers had 24" barrels. For the reloader, there is no performance advantage with either cartridge.
But 7mm Rem. Mag. brass is much more available than 7mm WSM brass. And brass for the Remington magnum is available from dozens of manufacturers, while only Winchester produces 7mm WSM cases. This is certainly an advantage for the 7mm Rem. Mag.
The 7mm WSM has not caught on as well as its .270 and .300 caliber siblings, and it is not offered in quite as many rifles. However, bolt action hunting rifles are available from several manufacturers including Browning, Ruger, Savage, and Winchester. In addition, Browning offers their BAR autoloader and BLR lever action models in 7mm WSM.
On the other hand, almost every model of bolt action rifle with a standard length action is available in 7mm Rem. Mag. The available rifle models include single shots, a couple of autoloaders, and the aforementioned BLR lever action. No other 7mm Magnum cartridge comes close in terms of the number and variety of available rifles. In availability of rifles, new or used, the 7mm Rem. Mag. has a big advantage.
One of the most heavily touted (hypothetical) advantages of the WSM cartridges is their "inherent" accuracy. Unfortunately, this is due more to their resemblance to the short, stubby cartridges popular in the world of bench rest target shooting, rather than any documented advantage in the field.
In the field, the difference between the intrinsic accuracy of these two rifle cartridges is so tiny (if it exists at all) that other factors are overwhelmingly more important. These include, but are not limited to, the rifle (barrel, bedding, action, trigger, care of assembly, etc.), the ammunition (the precision of the various components and the care with which they are assembled), the interaction of the individual rifle with the particular load chosen (hunting ammunition is normally chosen more for its ballistics and terminal performance on game than its accuracy), external conditions (wind, weather, temperature, altitude, etc.), the steadiness of the position from which a shot is fired (from an impromptu rest, prone, sitting, standing, etc.), and most of all the skill of the shooter. Because of these variables, some of which are huge, any attempt to cite superior intrinsic accuracy as a significant difference between the two cartridges is laughable.
Rifle size and weight
The whole point to the 7mm WSM is that it can be used in short action magnum rifles. In the past there have been very few short action rifles with magnum bolt faces, but that is now changing. Bolt action rifles from Browning, Remington, Ruger, Savage, Winchester and possibly others are now available for the various short magnum cartridges.
The difference between a standard length action for the 7mm Remington Magnum, and a short action for the 7mm WSM is about 1/2". Given the same barrel length, stock (length of pull) and so forth, a rifle chambered for the 7mm WSM should be about 1/2" shorter than an equivalent rifle in 7mm Rem. Mag. If the former is 44.5" in overall length with a 24" barrel, the latter should be 44.0" in overall length with a 24" barrel.
Because the short action rifle loses 1/2" out of its middle (action and stock), it is also slightly lighter. This is not always evident from the catalog weight of rifles, since the difference is so slight (usually just a couple of ounces). But other things being equal, it is there. The 2004 Remington catalog shows that their Model 700 BDL SS short magnum rifle with a 24" barrel weighs 7 3/8 pounds, while the standard length magnum version of the same rifle weighs 7 1/2 pounds. That is a 2 ounce difference in weight.
So there should be a difference in the overall length and weight of otherwise identical 7mm WSM and 7mm Rem. Mag. rifles. We can estimate that an otherwise identical 7mm WSM rifle is about 1/2" shorter and 2 ounces lighter.
The 1/2" shorter length is a slight advantage for the 7mm WSM. The difference in weight may or may not be an advantage. For carrying long distances, 2 ounces less weight is a slight advantage. When actually shooting the rifle, particularly during practice sessions at the range, 2 ounces less weight is a slight disadvantage, because less weight means more recoil. The important thing to remember is that in size and weight there is actually not much difference.
Because the 7mm WSM cartridge is fatter than the 7mm Rem. Mag. cartridge, an internal box magazine of the type found in most modern bolt action hunting rifles might hold one additional 7mm Remington Magnum cartridge. This depends on how the internal volume of a specific magazine compares to the volume occupied by the cartridges. In Savage rifles the 7mm WSM magazine capacity is 2 rounds, while the 7mm Rem. Mag. capacity is 3 rounds. In Winchester M70 rifles the magazine capacity in either caliber is 3 rounds, and in Browning A-Bolt II rifles the magazine capacity in either caliber is 4 rounds.
CXP2 and CXP3 game
In terms of effectiveness (killing power) on typical CXP2 game, such as deer, antelope, goats, wild sheep, feral hogs, black bear, red stag, and caribou there is no practical difference between the 7mm WSM and 7mm Rem. Mag. Nor is there any difference between the two cartridges when larger CXP3 class game is the quarry. Examples of typical CXP3 game include Scandinavian moose (alg), North American moose, elk, zebra, kudu, and wildebeest.
None of these animals are normally classed as dangerous game, and all can be humanely killed by a single well placed bullet from any 7mm Magnum rifle. Should a malfunction occur, which is unlikely, a trophy may be lost but no real harm is done. It is not a life and death matter to the hunter.
Hunting dangerous game, on the other hand, is an entirely different matter. I would not recommend the 7mm WSM cartridge for hunting any type of dangerous game. The ballistics of the 7mm WSM and 7mm Rem. Mag. are sufficient for all of the big predators (cats and bears) in most situations. Many grizzly bears and African lions, for example, have been taken with 7mm Magnum rifles.
But it would be foolish to choose a rifle in 7mm WSM when the same or a similar rifle is available in 7mm Rem. Mag. Even though the statistical difference in feed reliability is slight, it does exist. And anyone hunting dangerous game owes it to himself and to his tracker, guide, or some innocent person who may later cross a wounded animal's path, to eliminate all possible risk. A failure to feed when a follow-up shot is needed could potentially have disastrous consequences. Hunting dangerous game is a life and death matter, and it is often not the hunter, but a bystander, who ultimately pays the price when a problem occurs.
Any 7mm Magnum rifle is right at the maximum recoil limit for most shooters. Most 7mm Magnum fans won't admit it, but practically anyone can shoot better with a rifle that kicks less. Remember bullet placement is the most important factor in killing power. Literally any animal that can be killed by a well placed bullet from a 7mm Magnum can also be killed by an equally well placed bullet from a .280 Remington. A point to remember before you buy a new 7mm Magnum.
It has been alleged that the 7mm WSM kicks less for the same bullet weight at the same MV than the 7mm Rem. Mag. This is supposed to be due to its "more efficient powder burn." We have seen that in otherwise identical rifles the 7mm WSM should weigh about 1/8 pound less, and it is a physical fact that the less a rifle weighs the more it kicks. So how much difference is there in recoil between the two cartridges?
Lets say that our typical 7mm WSM rifle weighs 8 pounds 6 ounces (8.375 pounds), and our typical 7mm Rem. Mag. rifle weighs 8 pounds 8 ounces (8.5 pounds), both with identical 1 pound scopes and mounts. Most 7mm Magnums are at their best with bullets weighing about 150-154 grains. So let's compare the recoil of these middle weight bullets in the two cartridges. To be as fair as possible, let's compare them at identical velocities, using the same powder.
According to the sixth edition of the Hornady Handbook, 69.9 grains of AA MAGPRO powder can drive a 154 grain bullet to a MV of 3000 fps in the 7mm WSM. And 70.7 grains of the same powder can drive a 154 grain bullet to 3000 fps in the 7mm Rem. Mag. AA MAGPRO is the only powder listed in the Hornady Handbook that can drive 154 grain bullets to a MV of 3000 fps in both cartridges.
Using those loads for comparison, here are the recoil energy figures:
Judging by those numbers, I would have to say that there is no significant difference in the recoil of the two cartridges. Evidently the alleged "more efficient powder burn" in the 7mm WSM was less important than 2 ounces of additional rifle weight!
In four categories (depending somewhat on how you count) the two cartridges are essentially tied. In four others the 7mm Rem. Mag. emerged the winner. Only in overall rifle length was the 7mm WSM clearly superior (shorter), and then by only 1/2". Whether that 1/2" in rifle length is sufficient reason to select a cartridge that is inferior, or at best merely equal, in every other respect is your decision.
Copyright 2004, 2012 by Chuck Hawks. All rights reserved.