7.5mm Swiss (7.5 x 55mm)

7.5mm Swiss (7.5 x 55mm)

The 7.5×55mm Swiss, also known as the GP11, is a rimless bottleneck rifle cartridge developed in Switzerland in 1911 for use in military service rifles like the Schmidt-Rubin series and later the Karabiner Modell 1931 (K31). Known for its precision and performance, it was one of the most advanced military cartridges of its era, offering impressive accuracy and ballistic consistency.

This cartridge features a bullet diameter of approximately .308 inches, though early confusion arose due to the "7.5mm" name. Factory GP11 ammunition used a 174-grain full metal jacket boat-tail bullet, achieving velocities around 2,640 feet per second—remarkably high for its time. Reloaders often note the GP11’s near-match-grade consistency, making once-fired brass highly desirable for handloading.

In the reloading world, the 7.5×55mm Swiss benefits from modern component availability. Most handloaders opt for .308 diameter bullets, paired with powders such as H4350, IMR-4064, or Varget. The case is comparable in size and capacity to the .30-06 Springfield but designed for lower pressure rifles. Special care should be taken with older Schmidt-Rubin models, as they were not built to handle the higher pressures achievable with modern powders.

Accuracy is a hallmark of the cartridge. Shooters of surplus K31 rifles frequently report sub-MOA groupings with tuned handloads. The precision Swiss manufacturing, straight-pull bolt action, and well-balanced rifles have all contributed to the cartridge's lasting appeal among collectors and precision shooters alike.

Though no longer in military use, the 7.5×55mm Swiss remains popular for target shooting, hunting, and historical collecting. It exemplifies the Swiss approach to engineering: efficient, accurate, and enduring.

Source: Wolfe Publishing