in the Krag–Jørgensen or Swedish Mauser or similar older rifles. This warning is relevant as the Danish, Norwegian and Swedish national shooting organizations strive to keep the costs of participating in their shooting events reasonable. Their rulings restrict the use of very expensive highly specialized target rifles by allowing only the use of their respective (historic) military service rifles and the SIG Sauer 200 STR rifle. Because 6.5 mm (.264 in) bullets have relatively high ballistic coefficients, the 6.5×55mm has seen success in long range target matches of . The 6.5×55mm cartridge was widely used in fullbore biathlon competitions until 1975 (when it was replaced by the .22 Long Rifle (.22 LR) rimfire cartridge), because of its inherent accuracy and historical popularity with the Scandinavian nations who have dominated this sport. The 6.5×55mm was and is used for target shooting disciplines like F-Class and benchrest. The cartridge is also used by Scandinavian target shooters that use the Sauer 200 STR (Scandinavian target rifle) as their competition rifle. Metallic silhouette shooters also use the 6.5×55mm. In North America the 6.5×55mm was the third most frequently mentioned caliber for hunter rifle at the 2003 Metallic Silhouette Nationals. Wildcats The 6.5×55mm case is also used as the parent case for modified variants that are not officially registered with or sanctioned by C.I.P. or SAAMI. Such cartridges which use commercial factory cases are generally known as wildcats. By changing the shape of standard factory cases (decreasing case taper or changing the shoulder geometry) wildcatters generally increase the case capacities of the factory parent cartridge case, allowing more propellant to be used to generate higher velocities. Besides changing the shape and internal volume of the parent cartridge cases, wildcatters also change the original calibers. A reason to change the original caliber can be to comply with a minimal permitted caliber or bullet weight for the legal hunting of certain species of game. Because the 6.5×55mm offers a wide short cartridge case that can be easily reloaded, and hence be reused several times, it has been used by wildcatters. With the 6.5×55mm as the parent case wildcatters have created the 6.5×55mm Ackley Improved In the 6.5×55mm Ackley Improved the cartridge case capacity is raised to approximately 4.03 ml (62.2 g H2O). The Ackley Improved family of wildcat cartridges is designed to be easily made by rechambering existing firearms, and fireforming the ammunition to decrease body taper