Together with the 270 Weatherby Magnum, the 7mm Weatherby Magnum, and the 300 Weatherby Magnum, the 257 Weatherby Magnum were the earliest cartridges introduced by Roy Weatherby257 Weatherby ammo is known for its long range performance and is considered an accurate flat shooting rifle cartridge Initially due to the cartridge's highFactory Ammunition Weatherby currently list five loadings for the 257 featuring Hornady, Nosler and Barnes projectiles The light 87grain Hornady SP at 35fps is intended strictly for varmints while the 100 grain Interlock at 3602fps and 117 grain RNSP Interlock at 3305 are both intended for use on lighter medium gameSep 30, 18 · Compared to the 2506 Remington, the 257 Weatherby Magnum pumps out roughly 600 fp more energy at the muzzle and 150 to 0 fps more velocity One of the reasons the 257 Wby Mag goes so fast is its allowed pressure, 65,000 psi The 2506 is limited to 63,000 psi, the 65 Creedmoor 62,000 psi Weatherby Select Plus 257 Weatherby Mag 115 Gr