the largest of the standard length magnum cartridge family released by Winchester, which includes the somewhat obsolete .264 Winchester Magnum and the popular .338 Winchester Magnum. SAAMI recommends a 6 groove with a twist ratio of 1:14 with a bore Ø of and a groove Ø of with each groove having an arc length of . While case volume varies between manufacturers, the typical Winchester case capacity is 95 grain of H2O (6.17 cm3). Maximum recommended pressure given by SAAMI is 53,000 c.u.p. while the CIP mandates a maximum pressure of . Performance The original specifications for the cartridge called for a bullet to be fired at a velocity of through a barrel. Winchester achieved and surpassed this performance with their .458 Magnum cartridge. Current performance standards for the cartridge allow it to launch a bullet at a velocity of about through a barrel. The bullet is seen as the standard weight for a 45 caliber (11.43 mm) rifle bullet. This bullet has a sectional density of .341, which provides the bullet a high penetrative value at a given velocity. Among standard sporting cartridge bullets, the 45 caliber (11.43 mm) bullet has the highest sectional density. While bullets such as the 30 caliber (7.62 mm) bullet with a sectional density of .374 and even a 45 caliber (11.43 mm) with a sectional density of .409 exist these weights are not seen as a standard for those calibers. The .458 Winchester Magnum loaded with the solid bullet provides adequate penetration for dangerous game up to and including elephant. Due to the cartridge's relatively short case and powder column, longer bullets and those with a lower weight to length ratio—such as mono-metal bullets like the A-Square Monolithic Solid and the Barnes Banded Solids—may take up valuable powder space and lead to lower velocities and reduced performance. Hence, the reason for companies such as A-Square loading the .458 Winchester Magnum and even the .458 Lott with the Monolithic Solid instead of the , which is reserved for cartridges with large powder capacities such as the .450 Assegai and the .460 Weatherby Magnum. Bullets that tend to have a high weight to length ratios such as now discontinued Speer African Grand Slam solid tend to work better in the .458 Winchester Magnum. With modern powders the .458 Winchester Magnum is capable of launching a bullet at , a bullet at , a bullet at