8×60mm S

The 8x60mm S (the S means it is intended for 8.2 mm (.323 in) groove diameter bullets) is an uncommon rimless bottlenecked centerfire cartridge of German origin, dating back to the interbellum period between World War I and World War II. As is customary in European cartridges the 8 denotes the 8 mm bullet caliber and the 60 denotes the 60 mm (2.362 in) case length. The 8x60mm S can, due to its 83.6 mm (3.291 in) overall length, easily be chambered in standard sized Mauser 98 bolt action rifles.

History
After World War I, the Allied forces signed the Treaty of Versailles. This Treaty prohibited the use of standard military weapons and ammunition by Germany. However, civilian hunters didn't want to give up on this great round, so a new cartridge was designed by the German arms manufacturer Deutsche Waffen und Munitionsfabriken (DWM). Extending the 7.92x57mm Mauser cartridge case by 3 mm (2 mm of lengthened body plus 1 mm of lengthened neck) created the 8x60mm S. The 8x60mm S bullet diameter is 8.20 mm (.323 in) as found in the 8x57mm IS.

The new cartridge used the same bullet and therefore only the chamber of the rifle had to be modified (reamed out by 2 mm plus 1 mm of neck extension) to accommodate the slightly longer case. This operation was easily performed on Gewehr 98 and Karabiner 98k rifles.

8x60mm
Since this chamber reaming operation is also possible for earlier I-bore rifles, 8x60mm chambered rifles (without the S or any other further additions) also exist. 8x60mm rifles sport the earlier tighter 8.07 mm (.318 in) I-bore as found in the 8x57mm I.

To avoid potentially serious accidents, it is important to distinguish clearly between cartridges loaded for these two different bullet diameters, and only fire them in appropriately chambered/barrelled rifles.

Cartridge dimensions
The 8x60mm S has 4.16 ml (64 grains) H2O cartridge case capacity. A sign of the era in which the 8x60mm S was developed are the gently sloped shoulders. The exterior shape of the case was designed to promote reliable case feeding and extraction in bolt-action rifles, under extreme conditions.



8x60mm S maximum C.I.P. cartridge dimensions. All sizes in millimeters (mm).

Americans would define the shoulder angle at alpha/2 ≈ 14.1 degrees. The common rifling twist rate for this cartridge is 240 mm (1 in 9.45 in), 4 grooves, Ø lands = 7.89 mm, Ø grooves = 8.20 mm, land width = 4.40 mm and the primer type is large rifle.

According to the official with C.I.P. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) guidelines the 8x60mm S case can handle up to 405 MPa (58740 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.

Contemporary use
Mostly Mauser Gewehr 98 and Karabiner 98k rifles were rechambered for this caliber. Other rifles, not rarely based on the Mauser action, were chambered for this cartridge too.

The 8x60mm S offers compared to its parent cartridge, the 8x57mm IS, about 1 to 2% extra muzzle velocity due to its slightly larger case capacity and higher maximum operating pressure. This results in a flatter trajectory and better performance at longer range.

The popularity of the 8x60mm S peaked just after World War I and continued throughout the 1930s and 1940s. Today the cartridge is almost obsolete. No or very few rifles are produced for this round. Only two mainstream manufacturers (RWS and Prvi Partizan), along with some other smaller companies like Nolasco and Sologne, continue to produce the cartridge for hunting.

Loaded with short light bullets it can be used on small European game like roe deer and chamois. Loaded with long heavy bullets it can be used on big European game like boar, red deer, moose and brown bear. The 8x60mm S offers very good penetrating ability due to a fast twist rate that enables it to fire long, heavy bullets with a high sectional density. The 8x60mm S can be used in countries which ban civil use of former or current military ammunition. The 8x60mm S rimmed sister cartridge, the 8x60mm RS, is also not popular in central Europe for the same reasons as the 8x60mm S.

The 8x60mm S is very popular in European countries like France where the possession of rifles in their original military caliber is tightly regulated: It allows French licensed gun owners to possess rifles based on the Mauser Gewehr 98 system under the less constraining "hunting rifle" category.

The also rare 8x64mm S cartridge offers a comparable rechambering option for Mauser Gewehr 98 and Karabiner 98k rifles sporting 8 mm S-bores. Due to its larger case capacity the 8x64mm S chambering offers better ballistic performance than the 8x60mm S.

Handloaders can also produce this round, by altering a .30-06 Springfield case and using a standard 8 mm bullet. Prvi Partizan is a major supplier of brass components for European 8x60mm S Handloaders.