Compared: .325 WSM and .338 Win. Mag.
By Chuck Hawks
The 2005 Winchester (USRAC) catalog says this about the .325 WSM, "Combining the velocity of the .300 Win. Mag. with the knockdown power of the .338 Win. Mag." Winchester (Olin) advertising claims in their 2005 catalog that the .325 WSM delivers, ".338 Winchester Magnum performance." The 2005 Browning Master Catalog (Browning and USRAC are owned by the same holding company) describes the .325 WSM this way, ". . . featuring the flat trajectory of the of the .300 Win. and the powerful knockdown punch of the long action .338 Win. Mag.--without the punishing recoil and additional rifle weight."
Those kinds of statements (sometimes in slightly modified form like "hits as hard as the .338 Win. Mag.") have been repeated as if they were gospel in every review of the .325 WSM cartridge that I have read in the popular sporting press. Except, of course, in the Guns and Shooting Online article about the .325, which was not written as a promotional piece for the big, red "W." This allegation equating the .325 WSM with the .338 Win. Mag. has been made so many times that a comparison article became almost inevitable.
It is worth noting that while the .325 WSM is being promoted as a cartridge for hunting large and dangerous animals (elk, moose, and brown bear are specifically mentioned), based on its bore and bullet diameter (.315" and .323" respectively) it actually falls into the "small bore" caliber classification. Traditionally, 8mm has been the Continental European equivalent of the North American .300" bore (.308" bullet) and British .303" bore (.311" bullet) all-around cartridges. Of course, plenty of large game has been taken with .30, .303, and 8mm cartridges, as well as uncounted numbers of medium size game.
The true "medium bore" calibers intended specifically for use on heavy game start at a bore diameter of .330" and bullet diameter of .338" (which precisely describes the .338 Winchester Magnum), and run up to .375". Logically we should compare the .325 WSM to the .300 WSM, as the two cartridges are nearly identical, and what one can do the other can also do. But Winchester has chosen to market the .325 against the .338. So, if it seems somehow unfair to compare a small bore cartridge to a medium bore cartridge for hunting heavy game, don't blame yours truly, blame Winchester.
The .325 WSM
The .325 Winchester Short Magnum (WSM) was introduced in 2005. Winchester (Olin) actually tried to develop a .338 WSM, but ran into technical difficulties because of the cartridge geometry of the WSM case and the length of .338 bullets. In the end, the closest thing that they could manage was an 8mm cartridge.
The ".325" nomenclature of the new cartridge is both unusual and inaccurate. It is actually a .31 caliber according to the traditional system (bore diameter) by which the .270 WSM and .300 WSM were named. Thus the new cartridge should have been named the ".315 WSM," as that is its bore diameter.
The .325 WSM is actually a small bore hunting cartridge very similar to the various short and standard length .300 Magnums, or any of the standard European 8mm (7.9mm) cartridges. Ballistically the .325 WSM is nearly identical to the 8x68S. See my article "Compared: .325 WSM, 8x68S, and 8mm Rem. Mag." on the Rifle Cartridge Page for more on that subject.
Dimensionally the .325 WSM is identical to the .300 WSM, except that the .325 case is necked-up to accept regular 8mm (.323" diameter) bullets. The shoulder angle is 35 degrees, the rim diameter .535", and the base diameter .555". The maximum case length remains 2.10" and the cartridge overall length remains 2.860".
Winchester factory loads for the .325 WSM include a 180 grain Ballistic Silvertip bullet and a 200 grain Accu-Bond bullet in their premium Supreme ammunition line. In their standard Super-X line they offer a 220 grain Power Point bullet.
The 180 grain BST bullet (BC .394) has a catalog muzzle velocity (MV) of 3060 fps. The 200 grain Accu-Bond bullet has a catalog MV of 2950 fps. And the 220 grain Power Point bullet has a claimed MV of 2840 fps. All of these Winchester catalog velocity figures are averages taken from a 24" test barrel.
Chronographed from the 23" barrel of a Browning A-Bolt II rifle, the actual MV of the Winchester 200 grain factory load proved to be about 100 fps slower than claimed. The chronograph results from the 24" barrel of a Winchester Model 70 proved to be about 75 fps slower than claimed.
Reloaders in the U.S. have a satisfactory but somewhat limited selection of 8mm bullets. Available bullet weights include 125, 150, 170-175, 180-185, 200 and 220-225 grains, but most manufacturers only offer a choice of two or three of these weights. 150, 170, and 200 grain bullets are probably the most popular, since 8mm rifles are traditionally seen as an alternative to .30 caliber rifles.
The .338 Winchester Magnum
The .338 Winchester Magnum was introduced in 1958. It quickly became the favorite caliber of Alaskan guides and is commonly used to "back up" clients hunting the great Alaskan bears. Today the .338 Win. Mag. has a worldwide reputation, and ammunition can be purchased almost anywhere large or dangerous animals are hunted.
Because the .338 Mag. is a standard (.30-06) length cartridge with the typical belted magnum rim diameter of .532" it is adaptable to a great many rifles. In fact, almost all single shot, bolt action, and double rifles that chamber the 7mm Rem. Mag. and .300 Win. Mag. can also chamber the .338 Win. Mag. The .338 Winchester is, by far, the most popular of all medium bore cartridges.
Factory loads for the .338 Win. Mag. offer bullet weights of 200, 210, 225, 230, and 250 grains. Reloaders have all of these plus bullets of 175-180, 275, and 300 grains to choose from. Solids for thick-skinned dangerous game like buffalo are available, usually in 250 grain round nose style. Most manufacturers offer a good selection of bullet weights in .338 caliber.
Winchester loads their 200 grain Ballistic Silvertip spitzer bullet (BC .415) to a MV of 2,950 fps. Remington loads drive a 225 grain Core-Lokt spitzer bullet (BC .435) at a MV of 2,780 fps. Federal's Premium Safari Rifle load pushes a 250 grain Nosler Partition bullet (BC .473) at a MV of 2,660 fps. These loads are typical of those offered by American ammunition manufacturers.
All of these factory loads are chronographed in 24" test barrels. Fair enough, as most .338 Winchester Magnum rifles are, in fact, provided with 24" barrels.
For the purposes of this article I am going to compare the three most typical bullet weights for each cartridge. All figures are for Winchester factory loads. The selected loads are (caliber, bullet, MV, ME):
In the course of this article we will compare velocity, energy, trajectory, sectional density, bullet frontal area, killing power, recoil, and the availability of rifles and ammunition. We will also look at other factors that impact the suitability of these cartridges for their intended purpose of hunting heavy and/or dangerous game.
Velocity is an important factor in calculating kinetic energy, and has a major impact on trajectory. It is a little difficult to compare the .325 WSM and .338 Win. Mag. in terms of velocity, since they drive bullets of different diameter and weight. The one bullet weight factory loaded for both cartridges is 200 grains, and the muzzle velocity of the 200 grain bullets is identical in the two cartridges (2950 fps).
Energy is important because it indicates a bullet's ability to do work (damage, in this case). Energy powers bullet expansion and penetration, which in turn determine the extent of the wound cavity. Here are the energy figures at the muzzle, 100, and 200 yards (in foot pounds).
On the whole, there is little to choose between the two calibers in terms of kinetic energy. The .338 Mag. has a slight advantage with most loads at most distances, but considering that both calibers develop considerable energy with all loads, the difference is unlikely to be very significant in the field.
Trajectory is important because it makes it easier to hit the target at extended ranges. A flat trajectory is generally more important for long range, medium game cartridges than for cartridges intended for large and dangerous game. It is unwise to shoot at dangerous game at extended ranges and, in any case, big animals present big targets, reducing the need for ultra flat trajectory. 50 to 150 yards, for example, is considered a good distance for shooting dangerous game such as the great bears. As we shall see, both the .325 WSM and .338 Win. Mag. shoot plenty flat enough for their intended purpose.
The following trajectory figures were taken from the Winchester 2005 Ammunition catalog. They are based on a 200 yard zero with a scoped rifle (+/- inches @ yards).
Once again, there is little to choose between the two calibers. The .325 shoots slightly flatter with most loads at most distances, but the difference is so slight as to make no difference in the field, especially considering the size of the intended game. The difference between the highest and lowest velocity loads listed (180 grain .325 and 250 grain .338) amounts to only 1" in drop at 250 yards, which would be inconsequential even on a small whitetail deer, let alone the giant animals for which these calibers are intended.
Sectional density (SD) is calculated by dividing a bullet's weight (in pounds) by the square of its diameter (in inches). The higher the number, the longer the bullet will be in any given caliber.
SD matters because, other things being equal, the higher the SD the better the potential penetration of the bullet. And penetration, especially in heavy game, is a critical factor in killing power. A long wound channel destroys more tissue than a short one of the same diameter. A bullet that fails to penetrate into the vitals is unlikely to result in a quick kill--and may get the hunter mauled or trampled when hunting dangerous game.
Here are the sectional density figures for each of the bullets in our six factory loads. Remember that while .338 bullets really measure .338", .325 bullets actually measure .323".
Here we have a real difference. In every case, from lightest to heaviest, the .338" bullet is superior compared to its .323" counterpart. The difference between the 180 grain .323" bullet and 200 grain .338" bullet is not great, but the difference between the 200 grain .323" and 225 grain .338" bullets is significant, and the .338's advantage is even greater when the 220 grain .323" bullet is compared to the 250 grain .338" bullet.
These latter are the bullets in each caliber most likely to be selected for use on the largest and most dangerous game, such as Alaskan brown bear. The hunter who needs deep penetration should look to the .338 Magnum.
Bullet Frontal Area
Bullet frontal area is another important factor in killing power. For any given depth of penetration, a larger diameter wound channel destroys more tissue and will result in a quicker kill. Other factors being equal, when comparing two bullets of equal sectional density, the one with the greater cross sectional area will do the most damage. Increased bullet frontal (cross sectional) area is the primary advantage of the medium bore calibers over the small bores.
Naturally, all bullets of a given caliber have the same frontal area regardless of weight. Here is the cross sectional area (in square inches) of all .325 WSM (.323") and .338 Winchester Magnum (.338") bullets.
Once again we have a real difference, one that matters in the field. And it again favors the .338 Win. Mag.
Killing power is what medium bore cartridges are all about. They are intended to flatten large and dangerous game. Killing power is composed of a number of complex factors, some of which are not quantifiable. Obviously, any big game bullet must destroy a sufficient amount of vital tissue within the animal if it is to effect a quick kill. And a quick, humane kill should be the goal of every hunter.
Obviously, the hunter must choose an appropriate bullet for the job at hand, and get that bullet into the right place. Otherwise all the power in the world is wasted. So for the purposes of this discussion we are going to assume that the hunter does his job properly.
The hunter pursuing very large or dangerous game must be especially concerned with killing power, as his quarry is not easy to bring down. In the case of dangerous game, failure to "stop" may be punishable by death, so killing power must be taken very seriously. We will compare the killing power of our two cartridges in terms of Optimum Game Weight and the Rifle Cartridge Killing Power Formula.
Optimum Game Weight
Of the various systems with which I am familiar that attempt to quantify the killing power of rifle cartridges--and none of them are perfect--the one I that regard as most useful is Edward A. Matunas' Optimum Game Weight (OGW) formula. This defines the killing power of a cartridge and load in terms of the distance to and weight of the animal for which it is suited. Without going into the mechanics of the formula, which is not necessary here, the results do seem to agree fairly well with what experienced big game hunters have observed in the field.
I have worked out an extensive "Expanded Optimal Game Weight Table," which can be found on the Tables, Charts and Lists Page. Here are the maximum optimum distance (range in yards) figures for our six factory loads, calculated for 600 pound and 1000 pound animals.
Comparing the light, medium, and heavy bullets in each caliber, the .338 Win. Mag. has a longer optimum range than the .325 WSM for both 600 and 1000 pound game. Obviously, the .338 hits harder at all distances.
For example, at 100 yards the .325 WSM/220 grain factory load is optimum for 1223 pound game, while at the same distance the .338 Win. Mag. is optimum for a 1423 pound animal. And remember, we are using the catalog velocities for the .325 WSM loads, even though we know that .325 WSM rifles actually produce 70-100 fps less velocity than claimed.
Rifle Cartridge Killing Power Formula
Another method for calculating killing power is represented by the RCKP formula, which was specifically created to include all of the easily quantifiable factors identified with killing power (including velocity, kinetic energy, SD, bullet frontal area, and bullet weight). All of this is explained in more detail in the article "The Rifle Cartridge Killing Power Formula," which can be found on the Tables, Charts and Lists Page.
The primary redeeming factor to this system (beyond being fairly easy to calculate) is that it also seems to show a positive correlation to reality. The bigger the number, the greater the killing power. Here are the results for our six loads, calculated for a distance of 100 yards.
Once again, load for load the .338 Magnum is superior to the .325 WSM. This is not entirely surprising, as it is throwing a heavier bullet of larger diameter at only marginally less velocity. That is why true medium bore calibers are so good at what they do--put down the largest thin-skinned game, including dangerous species, with authority. The top medium bore calibers, which include the .338 Win. Mag., have also repeatedly proven themselves on dangerous CXP4 class game, particularly the bovines.
Admittedly, both the .325 WSM and .338 Win. Mag. have good killing power. For comparison, here are some RCKP numbers for other popular cartridges as commonly loaded: .30-06/180 grain = 52.8; 8x57 JS/195 grain = 53.0; .300 WSM/180 grain = 63.1; .300 Wby. Mag./200 grain = 85.9; .350 Rem. Mag./250 grain = 87.7
Browning ad copy claims that the .325 WSM can be used in lighter rifles and still kick less than the .338 Win. Mag. That is quite a claim, if true. Of course, since we have already found that the .338 Win. Mag. is the more powerful cartridge, it should come as no surprise that in rifles of the same weight it also kicks more. That is inevitable given the laws of physics. BUT, typical .338 Win. Mag. rifles are heavier than Browning .325 WSM rifles, and rifle weight reduces the effect of recoil.
There is an "Expanded Rifle Recoil Table" on the Tables, Charts and Lists Page, so let's take a look at the recoil figures in typical scoped rifles of each caliber. An average .338 Win. Mag. rifle probably weighs about 8.5 pounds with a scope. A Browning A-Bolt II Hunter in .325 WSM weighs about 7.5 pounds with a scope. So, those are the rifle weights we will use in the following recoil comparison. Recoil is measured in foot pounds of kinetic energy.
Lo and behold, load for load the .338 Mag. actually kicks slightly less than the .325 WSM. The extra pound of rifle weight completely cancelled out the lower power cartridge's advantage. Since the difference is only about 1/2 ft. lb., I doubt that most shooters are going to be able to tell the difference, but the Browning advertising claim appears to have been based on hype rather than scientific fact. Certainly anyone who can shoot a light Browning .325 rifle could shoot a standard weight .338 Magnum rifle.
Note that both of these cartridges kick far harder than most shooters can stand for any extended length of time. If the preferred recoil limit for the average shooter's comfort is 15 ft. lbs., these babies kick well over twice as hard as most shooters are comfortable with! All the power in the world is wasted if the shooter flinches and misses the target.
Availability of Rifles
This category is a "no contest." As of this writing the .325 WSM is available in the Browning A-Bolt II and Winchester Model 70 bolt action rifles, period. Kimber, Ruger and Savage chamber for some of the WSM cartridges and could potentially add the .325 WSM to the list. For that we will have to wait and see.
As far as I know, no European or other non-U.S. companies have shown any interest in the .325 WSM. Few gun shops bother to stock rifles in .325 WSM caliber, although a Browning or Winchester dealer could presumably order a rifle for a customer who wanted one.
The .338 Winchester Magnum, on the other hand, is available from most manufacturers of high powered rifles. Available actions include bolt, single shot, double, and autoloading. If a rifle maker offers a standard length action, you can probably get it in .338 Win. Mag. And even small town gun dealers are likely to stock .338 rifles.
Availability of Ammunition
Another "no contest." .338 Win. Mag. ammunition is stocked and sold around the world, wherever big game is hunted. Practically every gun shop stocks a selection of .338 Mag. ammo. The sporting goods department of my local Bi-Mart department store in Cottage Grove, Oregon (population about 8000) carries .338 Winchester Magnum ammunition, as do Wal-Mart stores and other sporting goods outlets across the U.S.
.325 ammunition is pretty much confined to full line, specialty gun shops. And some of them will have to special order it. Worldwide availability is practically nil. This is not the caliber to take on an African safari, and .325 ammo is not gonna be easy to find in Alaska, outside of the largest cities, either.
You will not read this in the print press, who are apparently afraid to offend their big advertisers, but the design of the WSM cartridges makes them less reliable than standard belted magnum cartridges to feed from the box magazines of typical bolt action rifles. The WSM's are not as bad in this regard as the WSSM's, but it is certainly a factor to consider for any rifle that may be used to hunt dangerous game.
If you want to see what a cartridge designed for reliable feeding from a bolt action rifle looks like, take a gander at the .375 H&H Magnum. A tapered cartridge with sloping shoulders is the ideal from the standpoint of feed reliability.
The squat, fat, rebated rim, sharp shouldered shape of the .325 WSM simply renders it mechanically less reliable than the .338 Winchester Magnum. I have gone into this in other articles, so I will not belabor it here. But I would not recommend the use of any WSM (or Remington SAUM) cartridge for hunting dangerous game. There are too many better choices, including the .338 Win. Mag.
If you have read this far you already know the "winner" of this comparison. The .325 WSM has the power to harvest large, non-dangerous animals such as elk and moose with well placed shots, no doubt about it. But the .338 Winchester Magnum is even better for the purpose.
For the North American hunter desiring a medium bore rifle for both large and possibly dangerous CXP3 game, the .338 is the obvious choice. Certainly it is the sensible choice for a rifle that also might be called upon, in a pinch, to shoot a dangerous CXP4 class game animal.
For the hunter who will journey beyond North America in pursuit of heavy game, the .325 WSM should not be considered. First of all, it is not a medium bore cartridge and will not qualify as such. Second, ammunition and support will be unavailable practically everywhere. Stick with the true medium bore calibers known and respected worldwide, such as the .338 Winchester Magnum and .375 H&H Magnum.
Copyright 2005, 2012 by Chuck Hawks. All rights reserved.