257 Roberts History and General Information.  The 257 Roberts was designed and introduced to the shooting public by Remington in 1934. The 257 Roberts was designed by Remington who was experimenting with the 25 Roberts cartridge at the time and trying to produce it commercially. In doing so they needed to make changes to the cartridge case itself.  The 25 Roberts cartridge was a 7x57mm cartridge case necked down to 25 caliber with a 15 degree shoulder angle, The Remington changes were, the shoulder was moved forward and the shoulder angle was changed to 20 degrees.  Remington was ready to introduce this new cartridge as the 25 Roberts except for the wisdom of Captain E. C. Crossman who stated at the time there would most likely be complications as the 25 Roberts was already being produced by custom gun makers and the chambers of the 2 cartridges were quite different and at that, Remington renamed the cartridge to 257 Roberts upon Captain Crossman's suggestion.  The 257 Roberts is a good dual purpose cartridge as it can be used for varmints sending a 75 grain bullet out the muzzle at 3,400 feet per second, making this a good varmint round or it can be used as a big game cartridge sending 100 grain bullets out the muzzle at speeds of 3,000 feet per second, it has sufficient power out to the 275 yard mark for deer sized game animals.  The 257 Roberts with the accuracy, power and effectiveness it offers down range recoils mild to moderate to the shooters shoulder and is recommended for those shooters who want more bullet frontal mass than the 24 calibers but don't want the recoil of a 25/06.   257 Roberts Barrel Specifications. Common Barrel Twist Rate - 1/10 Bore Groove Diameter - .257"   257 Roberts Reloading Specifications. Bullet Diameter - .257" Maximum Case Length - 2.233" Trimmed Case Length - 2.223" Primer Size - Large Rifle   257 Roberts Loading Data Hints.  The 257 Roberts responds well to powders such as i.m.r. 4064 and 4895 with excellent velocity consistency and accuracy. 257 Roberts Reloading Data. Hodgdon Reloading Data Center.   257 Roberts Trajectory and Hunting Applications.  This is a down range trajectory chart for the 257 Roberts cartridge with the scope mounted 1.5 inches above the bore center line plus if you were using this load, its effective hunting bullet energy range with well placed shots on, Varmint / Predator size game, such as Bobcat, Cougar, Coyote. Deer size game, such as Antelope, Blacktail, Hogs, Javelina, Mule, Whitetail. Elk size game, such as Caribou, Black Bear, Sheep. Moose size game, such as Brown Bear. Bullet diameter .257" Bullet weight 100 grains Bullet ballistic coeffecient .357 Bullet velocity 3,000 feet per second Range 100 yds. 200 yds. 300 yds. 400 yds. 500 yds. + + 1.6 0 - 7.3 - 21.9 - 45.4 1653 1357 1107 897 722  Varmint + + + + + +  Deer + + - - - -  Elk - - - - - -  Moose - - - - - - Copyright 2001 - 2010