Compared: The .25 WSSM and .25-06 Remington
By Chuck Hawks
Winchester introduced their .25 WSSM cartridge in 2004. I understand that the original intention was to base a new .25 caliber on the WSM (short action) case, which would have resulted in true magnum performance. But experiments with the prototype of that cartridge and its large pressure excursions convinced the Winchester brass that it was too touchy for release to the public. So experiments turned to the smaller WSSM (super short action) case. These were successful, and although the performance of the resulting cartridge could in no way be described as "magnum," that label was never the less attached for sales appeal.
The new marketing strategy was to sell the .25 WSSM against the established .25-06 Remington, a standard length (non-magnum) cartridge. But does the .25 WSSM really equal, let alone surpass, the performance of the .25-06? That is where this article comes in.
The .25 WSSM
Winchester introduced the .25 WSSM some 80 years after the design of the .25-06. It is based on a necked-up .243 WSSM case with a slightly different shoulder. Bullet diameter is .257". Cartridge overall length is about 2.35", and cases are trimmed to 1.66" by reloaders.
Winchester offers a Supreme varmint load that drives an 85 grain Nosler Ballistic Silvertip bullet at a MV of 3470 fps. And the Big Red W offers two loads for the .25 WSSM intended for hunting CXP2 class game. One of these is a Supreme 115 grain Ballistic Silvertip bullet at a MV of 3060 fps, presumably intended for the smaller species of CXP2 game. The other is a Super-X load using a 120 grain Positive Expanding Point bullet at a MV of 2990 fps.
Browning and Winchester make special super short action rifles for the WSSM series of cartridges. Both big game and varmint style rifles are offered. The varmint models come with 24" barrels; the sporter versions of the Browning A-Bolt II come with 21" barrels and the sporter versions of the Model 70 come with a 22" barrels. For more information, see my article "The .25 WSSM" on the Rifle Cartridge Page.
The .25-06 Remington
The .25-06 was a popular wildcat for many years, dating back to around 1920. Early on it was known as the ".25 Niedner" and later in its wildcat career as simply the .25-06. Remington finally adopted it as the .25-06 Remington and it became a SAAMI standardized cartridge in 1969.
The .25-06 is simply the rimless, bottleneck, .30-06 case necked-down to accept .257" diameter bullets. As standardized by Remington the shoulder angle remains 17.5 degrees, the rim diameter is .473", and the overall case length is 2.494". Cartridge overall length (COL) is 3.25".
Most of the major firearm manufacturers offer rifles in .25-06 caliber. In the U.S. these include, but are not limited to, Browning, Remington, Ruger, Savage, Weatherby, and Winchester.
Modern U.S. factory loads drive a 90 grain varmint bullet at a MV of 3440 fps, 100 grain bullets at 3210-3230 fps, and 115-120 grain bullets at a MV of 2990-3110 fps. Reloaders can duplicate most of these factory loads, and the selection of .257 bullets is good. Clearly the .25-06 is an excellent long range cartridge for CXP2 class game. For more information, see my article "The .25-06 Remington" on the Rifle Cartridge Page.
For purposes of comparison we will look at varmint and big game loads for each caliber. I would like to compare factory loads, but while certain other manufacturers load hotter .25-06 factory loads (particularly Hornady with their Light Magnum loads, which run about 100 fps faster than the Winchester offerings), Winchester has cleverly pegged their .25 WSSM loads to the exact same velocity as their .25-06 factory loads, or vise-versa.
So the cartridge comparison is over before it begins if we use Winchester factory loads. They are the same. The same bullets at the same velocity. End of story.
Reloads, however, tell a different story. The .25 WSSM is too new to have made it into my various reloading manuals, but fortunately the Hodgdon Powder Co. has made .25 WSSM reloading data available on their WebSite. Practically all reloading manuals cover the .25-06, so I will use the Nosler Reloading Guide, Fifth Edition as the source for .25-06 reloading data, since Winchester uses the same Nosler bullets in their factory loads for both calibers. Note that both Hodgdon and Nosler tested their reloads in 24" barrels, the same length as the SAAMI standard for both calibers. All of the reloads quoted below are maximum loads.
Here are the .25 WSSM reloads we are going to compare:
And here are the .25-06 Remington reloads to which we are going to compare them:
It is apparent from the ballistics above that the .25-06 can drive the same bullet about 100 fps faster than the .25 WSSM. That is not an earthshaking difference, but it is real. It means that the .25-06 will shoot flatter at all ranges.
Here are the maximum point blank ranges (MPBR) +/- 3" for our four reloads:
The difference in MPBR with the 85 grain varmint bullet is 8 yards in favor of the .25-06. The difference in MPBR with the 115 grain hunting bullet is 11 yards in favor of the .25-06.
That velocity edge also means that the .25-06 delivers more energy at all ranges. Either varmint load strikes with enough energy to obliterate a varmint at any distance it can be hit, so any difference in energy and killing power will be more important with the CXP2 game loads. Here are the energy figures (in foot-pounds) for the 115 grain bullets:
The .25-06's superiority in kinetic energy reaches 234 ft. lbs. at 300 yards. That strikes me as a meaningful difference.
Since the sectional density and bullet frontal area are the same for both calibers with the same weight bullet, any difference in killing power will be purely a result of velocity and energy. According to the Optimum Game Weight (OGW) formula devised by Edward A. Matunas and published in the Lyman 47th Reloading Handbook, here are the OGW (live weight in pounds) figures for our two CXP2 game loads at 100, 200, and 300 yards:
The .25-06 has an optimum game weight advantage of about 50-64 pounds at all ranges. That is a measure of the extra killing power inherent in the bigger cartridge.
At the time of this writing (the end of 2004), only Browning and Winchester chamber for the .25 WSSM, and only in their bolt action rifles. If the A-Bolt II or the Model 70 is your cup of tea, fine. If not, choose another caliber.
On the other hand, the .25-06 is available in a plethora of rifles. Most bolt action rifles with standard length actions are chambered for the .25-06, whether made in the U.S. or abroad. So are single shot rifles and the Browning BAR autoloader.
Only Winchester loads .25 WSSM ammunition. In my area it is hard to find and expensive. But all major U.S. ammunition manufacturers load .25-06 cartridges. It is widely available and less expensive than WSSM ammo. This also means that there are more types and weights of bullets available in .25-06 factory loaded ammunition. This is an important consideration for the hunter who relies on factory loads and must find the "right" bullet for best accuracy in his individual rifle.
The one advantage of the .25 WSSM cartridge is that it is used in an action about 1" shorter than the standard length action required for the .25-06. This may or may not (depending on your opinion) be offset by the fact that the very fat WSSM cartridge limits the magazine capacity of the Winchester Model 70 rifle to three rounds, as opposed to the five round capacity of Model 70's chambered for the .25-06.
Winchester Model 70 Featherweight specifications show that the WSSM models are actually 1.5" (rather than 1") shorter than the Featherweight models with standard length actions, (41" in overall length vs. 42.5"). Unfortunately, the extra 1/2" shorter overall length is due to a 1/2" reduction in length of pull, and has nothing to do with the caliber. Shortening the length of pull cramps an average size shooter and increases the subjective recoil effect, a poor way to "pad" the specification sheet.
It would seem difficult to avoid concluding that the .25 WSSM is ballistically inferior to the .25-06. In fact, it is inferior in every way except action length. The differences are not always large, but they are there. And sometimes the differences (for example in long range energy, rifle models, factory loads, and magazine capacity) are quite substantial.
Copyright 2004, 2012 by Chuck Hawks. All rights reserved.