.325 Winchester Short Magnum

.325 Winchester Short Magnum (also known as .325 WSM) is an 8 mm (.323 in) caliber rebated rim bottlenecked centerfire short magnum cartridge that was introduced in 2005 by Winchester. It is a member of the Winchester Short Magnum family of rifle cartridges.

The .325 Winchester Short Magnum was designed to take on the thick-skinned and heavy-shouldered big game animals found from Alaska to Africa. Combining the velocity of the .300 Winchester Magnum with the knockdown power of the .338 Winchester Magnum, the .325 Winchester Short Magnum offers the power needed to take on big game animals in a lighter short action rifle. Like all .300, 8 mm and .338-caliber magnum cartridges the .325 Winchester Short Magnum cannot be universally used on African game since certain sub-Saharan Africa countries have a 9.53 mm (.375 in) minimum caliber rule for hunting Big Five game.

Cartridge dimensions
The .325 Winchester Short Magnum has 5.39 ml (83 grain) H2O cartridge case capacity.



.325 Winchester Short Magnum maximum C.I.P. cartridge dimensions. All sizes in millimetres (mm).

Americans would define the shoulder angle at alpha/2 ≈ 35 degrees. The common rifling twist rate for this cartridge is 254 mm (1 in 10 in), 4 grooves, Ø of the lands = 8.00 mm, Ø grooves = 8.20 mm, land width = 4.47 mm and the primer type is large rifle.

According to the official C.I.P. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) rulings the .325 Winchester Short Magnum can handle up to 435 MPa (63,091 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers.

The .325 Winchester Short Magnum is a Delta L problem cartridge, meaning it can present unexpected chambering and/or feeding problems. The Delta L problem article explains this problem in more detail.

The German 8x68mm S cartridge introduced in 1939 is probably the closest ballistic twin of the .325 Winchester Short Magnum. The .325 Winchester Short Magnum is considerably shorter and fatter and has a more radical rebated rim, much steeper shoulder angle and a shorter neck (7.82 mm) than the 8x68mm S. This makes the 8x68mm S case with its 9.11 mm long neck better suited for loading long heavier bullets and due to its sleeker exterior shape bound to cycle more reliably in bolt action rifles in extreme situations. On the other hand the proportions of .325 Winchester Short Magnum promote good internal ballistic efficiency that allows the .325 Winchester Short Magnum to fire shorter lighter bullets at slightly higher muzzle velocities whilst using less propellant than the classically proportioned 8x68mm S.

8 mm cartridges compared
Maximum muzzle velocity comparison in % of the probably most proliferated European and American 8 mm rifle cartridges out of 650 mm (25.59 in) long barrels loaded with relatively light to heavy 8 mm bullets to their CIP or SAAMI (Sporting Arms and Ammunition Manufacturers’ Institute) sanctioned maximum pressures.

This comparison is not totally objective since the 8 mm Remington Magnum operates at 460 MPa (66717 psi, the .325 Winchester Short Magnum at 435 MPa (63,091 psi), the 8 x 68 S at 440 MPa (63817 psi), the 8 x 64 S at 405 MPa (58740 psi) and the 7.92 x 57 mm Mauser at 390 MPa (56564 psi) maximum chamber piezo pressure. Higher chamber pressure results in higher muzzle velocities.