.257 Roberts (using Hornady bullets)
Date: Feb 11 2014
N.H. "Ned" Roberts developed the .257 Roberts cartridge during the 1920s by necking the 7mm Mauser case to accept .257-inch bullets, and by changing the shoulder angle from 20 to 15 degrees. Roberts was a well-known experimenter and gun writer, and his cartridge became a popular wildcat among custom rifle builders and hunters. In 1934 Remington commercialized the Roberts cartridge and began offering factory rifles and ammunition. The shoulder angle was changed back to the original 20 degrees of the 7mm Mauser, but Remington gave proper credit to Roberts, reflected in the cartridge’s name.
The .257 Roberts, affectionately nicknamed "Bob," is an excellent deer cartridge that offers modest recoil and is capable of taking game in open country where longer shots are common. Most major manufacturers including Remington, Winchester, Savage, Ruger, Kimber and several others have offered rifles in this chambering.
The Roberts has been chambered in a variety of rifle action types including pump, Mauser Models 93 and 95, and other actions that are not as strong as modern bolt actions. For these reasons, industry standard pressure limits have been held to 45,000 CUP maximum. However, Winchester introduced a +P (higher pressure) load to the industry that features cases with thicker construction and loaded to a maximum average pressure of 50,000 CUP, which is intended only for modern rifles with strong actions. This breathed new life into the cartridge. As a result of improved +P ballistics, shooter interest has likewise been renewed. The data herein is +P, and should not be used in pump or weaker actions.
Another virtue of the Roberts includes its versatility to serve as a varmint/coyote cartridge or for deer sized game. In load development I found that it thrived on 75- through 120-grain bullets. Outstanding powders for 75- and 87-grain Hornady bullets included Hodgdon Varget, H-414, IMR-4064, IMR-4350, Winchester 760 and Alliant Reloder 15. For 100- to 120-grain bullets, many of the above powders likewise performed well; however, IMR-4831, Hodgdon Superformance, H-4350, H-4831, Alliant Reloder 17, RL-19 and RL-22 offered additional velocity and notable accuracy.