The .325 WSM
By Chuck Hawks
The new .325 Winchester Short Magnum (WSM) cartridge is actually a .315 caliber by bore diameter and a .323 caliber by groove (or bullet) diameter. It is an 8mm small bore cartridge, not a medium bore, and should not be regarded as such. 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".
Reloaders should note that there is a much smaller selection (at least in North America) of .323" bullets than of the .308" bullets used in all .300 Magnum cartridges. 8mm calibers have never caught on in North America because they are so similar to the vastly more popular .30 calibers.
It is becoming apparent that, for technical reasons (i.e. case shape), the much-ballyhooed Winchester Short Magnum is a rather limited design. Winchester tried, and failed, to neck it down to make a viable .25 caliber magnum (thus the introduction of the .25 WSSM instead of a .25 WSM), and failed again when they tried to neck it up to .33, the smallest of the medium bore calibers. Winchester technicians have admitted that the WSM case was optimized for .30 caliber bullets, and that its efficiency falls off rapidly as the caliber is decreased or increased. Evidently the utility of the WSM case lies between .27 caliber and .31 caliber, period. That said, the .325 WSM is a satisfactory cartridge for hunting non-dangerous CXP2 and CXP3 class game, animals from the size of deer and antelope to elk and moose, as long as the shooter can tolerate the substantial recoil.
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 has a catalog muzzle velocity (MV) of 3060 fps and muzzle energy (ME) of 3743 ft. lbs. The 200 grain Accu-Bond bullet has a catalog MV of 2950 fps and ME of 3866 ft. lbs. The 220 grain Power Point bullet has a claimed MV of 2840 fps and ME of 3941 ft. lbs. These Winchester velocity figures are averages taken from a 24" test barrel.
The trajectory of a .325 WSM rifle shooting a 180 grain Nosler Ballistic Tip bullet at an honest MV of 2975 fps should look like this: +2.6" at 100 yards, +2.0" at 200 yards, 0 at 245 yards, -4.1" at 300 yards, and -16.8" at 400 yards. The maximum point blank range (+/- 3") of that load is 289 yards.
The 200 grain Accu-Bond bullet, a bonded core design, will probably prove to be the most popular factory load for hunting large game. 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.
I would expect that the same powders that work well with the .300 WSM and .300 Rem. SAUM will also work in the .325 WSM. Velocities with bullets of equal weight should be slightly higher in the new 8mm cartridge because of its slightly larger bore diameter. Velocities with bullets of similar SD will be somewhat lower because such bullets must be heavier. (A .30 caliber, 180 grain bullet has a SD of .271, much the same as the SD of a 200 grain 8mm bullet.)
Reasonable bullets for medium size game like deer and pronghorn antelope will weigh about 150 grains. The 170-180 grain 8mm bullets should be a good choice for all-around use and mixed bag hunts. And for heavy game the 200-220 grain bullets can come into play.
Hodgdon reloading data shows that a 180 grain Nosler Ballistic Tip bullet can be driven at a MV of 2808 fps by 62.0 grains of H414 powder at a MAP of 54,400 PSI. A maximum load of 65.5 grains of H414 will drive the same bullet at 2946 fps with a MAP of 62,000 PSI. These loads were developed using Winchester cases, WLRM primers, and were tested in a 24" barrel.
Note: A full length article about the .325 WSM can be found on the Rifle Cartridge Page.
Copyright 2005, 2013 by Chuck Hawks. All rights reserved.