The .257 Roberts, also known as .257 Bob, is a medium-powered .25

caliber In guns, particularly firearms, but not #As a measurement of length, artillery, where a different definition may apply, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel Gauge ( ...

rifle cartridge. It has been described as the best compromise between the low

recoil Recoil (often called knockback, kickback or simply kick) is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, for according to Newton's third law the force requ ...

and flat

trajectory A trajectory or flight path is the path that an object with mass in motion follows through space as a function of time. In classical mechanics, a trajectory is defined by Hamiltonian mechanics via canonical coordinates; hence, a complete tra ...

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 The 7.62 mm caliber is a nominal caliber used for a number of different cartridge (weaponry), cartridges. Historically, this class of cartridge was commonly known as .30 caliber, the equivalent in imperial unit, Imperial and United States ...

(.30 in).The .257 Roberts (.257 Roberts +P) by Chuck Hawks
(membership required) Nominal bullet diameter of the .257 Roberts is .257 inches. 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 in or 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 The 7×57mm Mauser (designated as the 7 mm Mauser or 7×57mm by the SAAMI and 7 × 57 by the C.I.P.) is a first-generation smokeless powder rimless bottlenecked rifle cartridge. It was developed by Paul Mauser of the Mauser company in ...

case was a common choice, having near ideal volume capacity for the "quarter-bore" (0.25 in; 6.35 mm) using

powders A powder is a dry solid composed of many very fine particles that may Particle-laden flow, flow freely when shaken or tilted. Powders are a special sub-class of granular materials, although the terms ''powder'' and ''granular'' are sometimes use ...

available at that time. Ned Roberts is usually credited with being the designer for this cartridge. Eventually, in 1934,

Remington Arms Remington Arms Company, LLC, was an American firearms manufacturer, manufacturer of firearms and ammunition. It was formerly owned by the Remington Outdoor Company, which went bankrupt in 2020 with its lines of business sold to several purchase ...

chose to introduce their own commercial version of such a cartridge, and although it was not the exact dimensions of the

wildcat The wildcat is a species complex comprising two small wild cat species: the European wildcat (''Felis silvestris'') and the African wildcat (''F. lybica''). The European wildcat inhabits forests in Europe, Anatolia and the Caucasus, while th ...

made by Roberts, they called it the ".257 Roberts". From its introduction until the appearance of 6 mm cartridges such as .243 Winchester and

6mm Remington The 6mm Remington rifle cartridge, originally introduced in 1955 by Remington Arms Company as the .244 Remington, is based on a necked down .257 Roberts cartridge (itself a necked-down 7×57mm Mauser) using a .24/6mm bullet. Known for a combi ...

, it was a very popular general purpose cartridge.The .257 Roberts by Chuck Hawks
/ref> Today, although surpassed in popularity by other cartridges, it lives on with

bolt-action Bolt action is a type of manual Action (firearms), firearm action that is operated by ''directly'' manipulating the bolt (firearms), turn-bolt via a cocking handle, bolt handle, most commonly placed on the right-hand side of the firearm (a ...

rifles being available from some major manufacturers.

Conversion of war-souvenir Japanese Arisaka rifles

Japanese Type 38

Arisaka The Arisaka rifle () is a family of Japanese military bolt-action service rifles, which were produced and used since approximately 1897, when it replaced the Murata rifle (, ) family, until the end of World War II in 1945. The most common model ...

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 Handloading, or reloading, is the practice of making firearm cartridges by manually assembling the individual components (metallic cartridge, metallic/polymer-cased ammunition, polymer case, primer (firearms), primer, propellant and projectile) ...

6.5 mm bullets. The modified Roberts cases are sometimes known as "6.5×.257 Roberts", although the case

headstamp A headstamp is the markings on the bottom of a cartridge case designed for a firearm. It usually tells who manufactured the case. If it is a civilian case it often also tells the caliber: if it is military, the year of manufacture is often added ...

may still indicate .257 Roberts. Neither unmodified .257 Roberts ammunition nor the original 6.5×50mm Arisaka ammunition are suitable for firing in rechambered Arisaka rifles.

Performance

With light bullets, the .257 produces little recoil, and has a flat trajectory suitable for

varmint hunting Varmint hunting or varminting is the practice of hunting vermin — generally small/medium-sized wild mammals or birds — as a means of pest control, rather than as games for food or trophy. The targeted animals are culled because they are ...

. With heavier bullets it produces more recoil, but is capable of taking all but the largest North American game animals. The original factory load for this is very similar to the .250-3000 Savage.

Improved cartridges

Remington introduced the commercial version of this popular

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 The Sporting Arms and Ammunition Manufacturers' Institute (SAAMI, pronounced "Sammy") is an association of American manufacturers of firearms, ammunition, and components. SAAMI is an accredited standards developer that publishes several A ...

maximum pressure limit of compared to the listed for the standard .257 Roberts. It is also the only rifle cartridge with an official "+P" designation.

P.O. Ackley Parker Otto Ackley (May 25, 1903 – August 23, 1989) was an American gunsmith, barrel maker, author, columnist, and wildcat cartridge developer. The Ackley Improved family of wildcat cartridges are designed to be easily made by rechambering exi ...

said that the .257 Roberts Ackley Improved was probably the most useful all-around cartridge. 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 Muzzle may refer to: * Muzzle (anatomy) or snout, the projecting parts of the face (including the nose and mouth) of an animal ** Muzzle (mouth guard), a device that covers an animal's snout * Muzzle (firearms), the mouth of a firearm * Muzzle (ba ...

and muzzle energies for a test barrel, except .250-3000 Savage, which is for a test barrel and .257 Weatherby Magnum, which is for a test barrel.

References

External links

.257 Roberts at Reloaders Nest

{{DEFAULTSORT:257 Roberts Pistol and rifle cartridges Remington Arms cartridges Wildcat cartridges