7.5 x 55 Schmidt Rubin
From Wikipedia, the free encyclopedia
The 7.5x55 Schmidt Rubin (or 7.5 mm Swiss) is a cartridge developed for the Swiss Army by Eduard Rubin for rifles based on Rudolf Schmidt's action design.
NOTE GP11 ammunition should never be fired in older Schmidt-Rubin rifles such as the 1889 rifle. Use only GP90 ammunition in these.
[edit] General information
The 7.5x55 cartridge has been in Swiss Army service since 1889. Originally using a semi-smokeless powder it was known as the Gewehrpatrone 1890 (GP90). It was discovered that the primer of GP90 ammunition was far too corrosive so it was updated to the GP 1890/03 cartridge. This cartridge was updated still using smokeless powder and called the GP 1890/23.
In 1913 the metallurgy in Schmidt-Rubin rifles had advanced enough that a more powerful cartridge could be used. The 7.5 Swiss round was updated to the Gewehrpatrone 1911 (GP11). GP11 ammunition was used in the K11 and K31 carbines as well as the Stg.57 assault rifle. The cartridge saw service until the mid-80s. GP11 is regarded as highly accurate and well manufactured ammunition.
[edit] Specifications
GP90 GP90/03 GP90/23 GP11
Cartridge 7.5x53.5 7.5x53.5 7.5x54.5 7.5x55
Case Length 2.106" 2.106" 2.15" 2.185"
Rim Diameter .492" .492" .5" .496"
Head Diameter .488" .488" .496" .493"
Neck Diameter .362"
(w/ paper patch) .362"
(w/ paper patch) .328" .335"
Bullet 211gr 211gr 190gr 174gr
Paper Paper CuNi CuNi
patched patched Jacketed Jacketed spire-point boat-tailed
steel-capped steel-capped round nose
lead round nose lead round nose
Bullet Diameter .3208"
(w/ paper patch) .3208"
(w/ paper patch) .3075" .3086"
Bullet Length 1.14" 1.14" 1.165" 1.378"
Muzzle Velocity 1968 fps 1980 fps 2050 fps 2560 fps
Powder Measure 27-31gr 31gr 33.7gr 49.35gr
Semi-Smokeless Semi-Smokeless Smokeless Smokeless
Powder (PC88) Powder (PC88) Powder Powder
Max. Chamber Pressure 36,970 psi 36,970 psi 38,390 psi 45,500 psi
