The full metal jacket GP 11 boat tail spitzer bullet was when adopted an innovative bullet design. The GP 11 bullet contained a lead-antimony core and its jacket was made of plated steel or tombac. Depending on the year of production the plating was made of copper, brass, nickel or copper-nickel. The GP 11 cartridge cases were made of brass (72% of copper and 28% zinc) or, from May 1943 to January 1947, due to supply shortages in Switzerland, of aluminum or steel. The GP 11 bullet offered good aerodynamic efficiency and ballistic performance with a ballistic coefficient (G1 BC) of 0.505 to 0.514. At muzzle velocity the standard GP 11 ball bullet retained supersonic velocity up to (V800 ≈ Mach 1.1) under ICAO Standard Atmosphere conditions at sea level (air density ρ = 1.225 kg/m3). Even by 2011 standards, typical effective range is quite remarkable for a standard military rifle round that is more than a century old.