with a spitzer bullet fired at a muzzle velocity of with muzzle energy from a long barrel became available. Besides a pointed nose this projectile also had a boat tail to reduce drag. It had a maximum range of . Reverse engineering the trajectory from the previous sentence indicates a ballistic coefficient (G1 BC) of approximately 0.54. Military users At one time, the 7×57mm Mauser cartridge saw widespread military use. It was used by: :User Repetiergewehr M.14. in WWI El Salvador Iran Chambered service weapons Mauser Model 1893, Mauser Model 1895 and Mauser Model 1899, Mauser Model 1907, Mauser Model 1908, Mauser Standardmodell, vz. 24, Mondragón rifle, FN Mauser M1930, FN Model D, Remington Rolling Block, Venezuelan FN Model 1949, Hotchkiss Model 1922 machine gun, Madsen machine gun, Colt R75 Browning Automatic Rifle model 1925, M1941 Johnson, ZB vz.26, Type 3 heavy machine gun. Use as a parent case 6.5×57mm Mauser was created by Paul Mauser himself by necking down the 7×57mm already in 1890s. 5.6×57mm was created by RWS in 1960s in a similar way. Both cartridges also have rimmed variants for break-action hunting rifles, 6.5×57mmR and 5.6×57mmR respectively. The .257 Roberts uses the 7×57mm Mauser as its parent cartridge. The 6mm Remington is also based on the 7×57mm Mauser cartridge. The 7x57mm Mauser was also the parent case of the 6x57mm Mauser developed in 1895. Wildcats The 7×57mm Mauser is also used as the parent case for a host of modified variants that are not officially registered with or sanctioned by C.I.P. or its American equivalent, SAAMI. These cartridges are known as wildcat cartridges. The US wildcat cartridge developer P.O. Ackley developed several 7×57mm Mauser based wildcat cartridges. The 7×57mm Mauser Ackley Improved is an alternate version of the 7×57mm Mauser cartridge with 40 degree shoulder. This wildcat was designed to be easily made by rechambering existing firearms, and fire forming the ammunition to decrease body taper and increase shoulder angle, resulting in a higher case capacity. Dies for this wildcat chambering are readily available. The .228 Ackley Magnum is also based on the 7×57mm Mauser cartridge but is also necked down to .228 caliber (5.79 mm). Bullets in this caliber are hard to find but provide greater weight than .223 caliber bullets, up to 100 grains (6.5 g), without excessively quick twist rate. The .257 Roberts Ackley Improved is a second generation wildcat cartridge based on the