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

caliber In guns, particularly firearms, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel bore – regardless of how or where the bore is measured and whether the finished bore ma ...

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, as according to Newton's third law the force r ...

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 tr ...

of smaller calibers such as the 5 mm (.22") and 6 mm (.24"), and the higher energy but harder recoil of larger popular hunting calibers, such as the

7 mm 7 mm may refer to: Rail transport modelling * 7 mm scale, 1:43.5 scale with rails apart, representing standard gauge * HOn2 gauge, 1:87.1 scale with rails apart, representing narrow gauge Firearms * 7 mm caliber This is a list of firearm ...

(.28") family and the popular 7.62 mm (.30").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" or 6.35mm.

History

Many cartridge designers in the 1920s were creating various 6.35 mm (.25) 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 1 ...

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 idea. Eventually in 1934 Remington Arms chose to introduce their own commercial version of such a cartridge, and although it wasn't 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 the ...

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, 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 firearm action that is operated by ''directly'' manipulating the bolt via a bolt handle, which is most commonly placed on the right-hand side of the weapon (as most users are right-handed). Most bolt-actio ...

rifles being available from some major manufacturers.

Conversion of war-souvenir Japanese Arisaka rifles

Japanese Type 38 Arisaka rifles brought to the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

as wartime

souvenir A souvenir (), memento, keepsake, or token of remembrance is an object a person acquires for the memories the owner associates with it. A souvenir can be any object that can be collected or purchased and transported home by the traveler as a ...

s 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. 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 cons ...

. 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 The .250-3000 Savage (also known as the .250 Savage) is a rifle cartridge created by Charles Newton in 1915. It was designed to be used in the Savage Model 99 hammerless lever action rifle. The name comes from its original manufacturer, 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 maximum pressure limit of compared to the listed for the standard .257 Roberts. P.O. Ackley 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 velocity is the speed of a projectile (bullet, pellet, slug, ball/ shots or shell) with respect to the muzzle at the moment it leaves the end of a gun's barrel (i.e. the muzzle). Firearm muzzle velocities range from approximately to ...

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