.257 Roberts

Rifle cartridge January 2025 .257 Roberts 257 Roberts.JPG 300px United States Rifle Ned Roberts 1920s Remington Arms 1934–present .257 Roberts +P.257 Roberts Ackley Improved 7×57mm Mauser Rimless, bottleneck .257 .290 .430 .472 .473 2.233 2.775 1-10" Large rifle 54000 SAAMI 58000 SAAMI (+P) 75 HP 3450 1983 100 B-TIP 3020 2025 117 SPBT 2840 2096 24 Accurate Powders Accurate Powder Reloading Data Guide, 5th ed. http://www.accuratepowder.com/wp-content/uploads/2010/09/WP_LoadSpec_7-2-13.pdf Western Powders 12 July 2013 29–30 https://web.archive.org/web/20131101051706/http://www.accuratepowder.com/wp-content/uploads/2010/09/WP_LoadSpec_7-2-13.pdf 2013-11-01 live The .257 Roberts, also known as .257 Bob,https://www.americanrifleman.org/articles/2013/7/19/a-classic-returns-in-257-bob/ An Official Journal of the NRA | A Classic Returns in .257 Bob is a medium-powered .25 caliber rifle cartridge. It has been described as the best compromise between the low recoil and flat trajectory of smaller calibers such as the 5 mm (.22 in) and 6 mm (.24 in), and has more energy, but is harder recoiling, similar to larger hunting calibers, such as the 7 mm (.28 in) and 7.62 mm (.30 in).The .257 Roberts (.257 Roberts +P) by Chuck Hawks (membership required) Nominal bullet diameter of the .257 Roberts is .257 inches (6.5 mm). The .257 Roberts uses the same caliber bullets as .250 Savage or the more powerful .25-06 Remington. Barrel rifling diameter, from which calibers derive their designations, is 0.250 inches (6.35 mm). History Many cartridge designers in the 1920s were creating various 6.35 mm (.25 in) caliber cartridges. Due to the availability of inexpensive Mauser actions, the 7×57mm Mauser case was a common choice, having near ideal volume capacity for the "quarter-bore" (0.25 in; 6.35 mm) using powders available at that time. Ned Roberts is usually credited with being the designer for this cartridge. Eventually, in 1934, Remington Arms chose to introduce their own commercial version of such a cartridge, and although it was not the exact dimensions of the wildcat made by Roberts, they called it the ".257 Roberts".Barnes Frank C. McPherson, M.L. Cartridges of the World 8th 1965 1997 DBI Books 64, 91 0-87349-178-5 From its introduction until the appearance of 6 mm cartridges such as .243 Winchester and 6mm Remington, it was a very popular general purpose cartridge.The .257 Roberts by Chuck Hawks Today, although surpassed in popularity by other cartridges, it lives on with bolt-action rifles being available from some major manufacturers.March 2025 Conversion of war-souvenir Japanese Arisaka rifles Japanese Type 38 Arisaka rifles brought to the United States as wartime souvenirs were sometimes converted by rechambering to utilize more readily available .257 Roberts cartridge cases because commercially produced 6.5×50mm Arisaka cartridges were scarce prior to distribution by Norma Projektilfabrik A/S. The neck of the Roberts case would be slightly enlarged to accept handloaded 6.5 mm bullets. The modified Roberts cases are sometimes known as "6.5×.257 Roberts", although the case headstamp may still indicate .257 Roberts.Speer Wildcat Rifle Loads Speer Products Company (1956) p.35 Neither unmodified .257 Roberts ammunition nor the original 6.5×50mm Arisaka ammunition are suitable for firing in rechambered Arisaka rifles.Davis, William C., Jr. Handloading National Rifle Association (1981) 0-935998-34-9 p.170 Performance With light bullets, the .257 produces little recoil, and has a flat trajectory suitable for varmint hunting. With heavier bullets it produces more recoil, but is capable of taking all but the largest North American game animals..257 Roberts https://www.ballisticstudies.com/Knowledgebase/.257+Roberts.html 2025-10-01 www.ballisticstudies.com The original factory load for this is very similar to the .250-3000 Savage. Improved cartridges Remington introduced the commercial version of this popular wildcat as a low-pressure round. At the time there were many older actions available of questionable strength. With a modern action and handloading, this cartridge is capable of markedly improved performance. One of the common improvements is called the ".257 Roberts +P" which has a SAAMI maximum pressure limit of 58000 psi MPa compared to the 54000 psi MPa listed for the standard .257 Roberts. It is also the only rifle cartridge with an official "+P" designation.SAAMI Velocity & Pressure Data: Centerfire Rifle http://www.saami.org/specifications_and_information/specifications/Velocity_Pressure_CfR.pdf SAAMI 5 Alan Serven 2013-07-12 https://web.archive.org/web/20130702015600/http://saami.org/specifications_and_information/specifications/Velocity_Pressure_CfR.pdf 2013-07-02 dead P.O. Ackley said that the .257 Roberts Ackley Improved was probably the most useful all-around cartridge.Ackley P. O. Loading Data - Rifle Ackley P. O. Handbook for Shooters and Reloaders 1962 Publishers Press Salt Lake City, Utah 5158681 https://archive.org/details/bwb_S0-EFM-965/ registration 336–337 Making an Ackley Improved cartridge usually meant modifying the chamber to have a steeper shoulder and blown-out sides to provide greater powder capacity while still allowing factory ammunition to be fired safely. Comparison Data below shows sample muzzle velocities and muzzle energies for a 24 in cm flip test barrel, except .250-3000 Savage, which is for a 22 in cm flip test barrel and .257 Weatherby Magnum, which is for a 26 in cm flip test barrel. +Quick .25 in (6.35 mm) caliber comparison chart Cartridge Bullet weight (g) Bullet weight (gr) Muzzle velocity (m/s) Muzzle velocity (ft/s) Muzzle energy (J) Muzzle energy (ft·lbf) .250-3000 SavageNosler Reloading Guide 7, 250-3000 Savage http://www.nosler.com/250-3000-savage Nosler 12 July 2013 https://web.archive.org/web/20130708042942/http://www.nosler.com/250-3000-savage 2013-07-08 live 100 gr g table on flip 2911 ft/s m/s table on flip 1882 ft.lbf J table on flip .257 Roberts 100 gr g table on flip 3020 ft/s m/s table on flip 2025 ft.lbf J table on flip .257 Roberts +P 100 gr g table on flip 3090 ft/s m/s table on flip 2120 ft.lbf J table on flip .257 Roberts Ackley Improved Nosler Reloading Guide 7, 257 Roberts Ackley Improved http://www.nosler.com/257-roberts-ackley-improved Nosler 12 July 2013 100 gr g table on flip 3226 ft/s m/s table on flip 2311 ft.lbf J table on flip .25 WSSM 100 gr g table on flip 3313 ft/s m/s table on flip 2438 ft.lbf J table on flip .25-06 Remington 100 gr g table on flip 3324 ft/s m/s table on flip 2454 ft.lbf J table on flip .257 Weatherby Magnum 100 gr g table on flip 3512 ft/s m/s table on flip 2739 ft.lbf J table on flip See also 6 mm caliber Delta L problem List of rifle cartridges Table of handgun and rifle cartridges References External links .257 Roberts at Reloaders Nest .257 Roberts (257 Roberts +P) at The Reload Bench Category:Pistol and rifle cartridges Category:Remington Arms cartridges Category:Wildcat cartridges