One box of 20 cartridges: 257 Robertsby Hornady, factory production loaded using newcases with “HORNADY 257 ROB+P” Head-Stamp (+P for extra power or magnum load) and loaded with the 117 grain SST (Plastic Capped Jacketed Hollow Point) projectile. Please Note: single cartridges available, see below in related items.History of 257 Roberts cartridge:The 257 Roberts original began as a wildcat cartridge which was designed by N.H. Roberts (a well known firearm writer at the time). It was produced by necking down the 7×57 Mauser (.284″ Cal.) cartridge to 257″ caliber.For many years the 257 Roberts was referred to as the most useful (all around) rifle cartridge, for use on varmint, antelope, black bear, deer, sheep and goat.Under loaded by most ammunition companies for many years, it is now available in the more powerful +P loads in velocities up to 3850 feet per second and energy up to 2,134 foot pounds per square inch.It was quickly picked up by Winchester and Remington, who produced rifles and ammunition commercially for the general public.Remington even (incorrectly) named it the 257 Remington for a short time.
