8×68mm S

The 8×68mm S rebated rim bottlenecked centerfire rifle cartridge was developed in the 1930s by August Schüler of the August Schüler Waffenfabrik, Suhl, Germany as a magnum hunting cartridge that would just fit and function in standard-sized Mauser 98 bolt-action rifles.

The bore has the same lands and grooves diameters as the German 7.92×57mm Mauser service cartridge (designated as "S-bore").

The German ammunition manufacturer Rheinisch-Westfälische Sprengstoff-Fabriken (RWS) [de] introduced both cartridges commercially in the spring of 1939.

In properly adapted standard military Gewehr 98 or Karabiner 98k service rifles the large 8×68mm S cartridges are however praised for very smooth and reliable feeding.

The widespread availability of standard size Mauser 98 rifles and the fact that the .375 H&H Magnum cartridge and its necked down version the .300 H&H Magnum with approximately 72 mm (2.83 in) case length were too long to fit in standard sized Mauser 98 bolt-action rifles makes the shorter 8×68mm S, 6.5×68mm and .375 Hölderlin interesting chambering options.

(Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) guidelines the 8×68mm S case can handle up to 440.00 MPa (63,817 psi) piezo pressure.

regulated countries are currently (2014) proof tested at 550.00 MPa (79,771 psi) PE piezo pressure.

[2] The American .325 WSM cartridge introduced in 2005 is probably the closest ballistic twin of the 8×68mm S. The .325 WSM is considerably shorter and fatter and has a more radical rebated rim (P1 -R 1 = 0.51 mm), much steeper shoulder angle (70 degrees / 35 degrees for Americans) and a shorter neck (7.82 mm).

For a magnum chambering it also offers a tolerable amount of barrel wear, which is important to users that fire many rounds a year.

The 8×68mm S has a good long range accuracy reputation i.e. it is not hard to develop or find loads that will shoot 1 MoA or better out of decent standard mass-produced rifles.

This twist rate was chosen since the bullet jackets used in the 1930s were not strong enough to cope with the forces generated by the magnum muzzle velocities of the 8×68mm S. The 240 mm (1 in 9.45 in) twist rate normally found in the 8×57mm IS makes the 8×68mm S combined with modern bullets with jackets designed for magnum cartridges an excellent long range cartridge.

[4] This means that loaded with light, short and soft-nosed 8 mm bullets the 8×68mm S can be used on remarkably small game.

certified and became an officially registered and sanctioned under the 375 Hölderlin designation member of the German 68 mm "family" of magnum rifle cartridges.

Practically there can be some muzzle velocity gained by this method, but the measured results between parent cartridges and their 'improved' wildcat offspring is often marginal.

It is often reported that modern 68 mm RWS brass can tolerate up to 500 MPa (72519 psi) piezo pressure.

Because the 8×68mm S offers an exceptional sturdy, pressure resistant cartridge case that can relatively easily be reloaded with primers, powder and bullets and hence be reused several times it has become quite popular amongst wildcatters.

Michael W. Mayerl from the Styria Arms company[12] in Austria in 2005 as a reliable beltless high power cartridge for Mauser 98 rifles.

The throat of the .300 Styria Magnum is similar to the proven .308 Winchester and short enough to seat the bullets to the lands without exceeding the maximum length of 84.8 mm (3.339 in) to fit the original Mauser 98 magazine.

The thick-walled 8×68mm S parent case manufactured by RWS can handle a usage piezo pressure up to 460 MPa (66717 psi).

A Blaser R8 Custom Grade II straight-pull bolt action hunting rifle chambered in 8×68mm S