.257 Roberts | ||||||||||||||||
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Type | Rifle | |||||||||||||||
Place of origin | United States | |||||||||||||||
Production history | ||||||||||||||||
Designer | Ned Roberts | |||||||||||||||
Designed | 1920s | |||||||||||||||
Manufacturer | Remington Arms | |||||||||||||||
Produced | 1934–present | |||||||||||||||
Variants | .257 Roberts +P, .257 Roberts Ackley Improved | |||||||||||||||
Specifications | ||||||||||||||||
Parent case | 7×57mm Mauser | |||||||||||||||
Case type | Rimless, bottleneck | |||||||||||||||
Bullet diameter | .257 in (6.5 mm) | |||||||||||||||
Neck diameter | .290 in (7.4 mm) | |||||||||||||||
Shoulder diameter | .430 in (10.9 mm) | |||||||||||||||
Base diameter | .472 in (12.0 mm) | |||||||||||||||
Rim diameter | .473 in (12.0 mm) | |||||||||||||||
Case length | 2.233 in (56.7 mm) | |||||||||||||||
Overall length | 2.775 in (70.5 mm) | |||||||||||||||
Rifling twist | 1-10" | |||||||||||||||
Primer type | Large rifle | |||||||||||||||
Ballistic performance | ||||||||||||||||
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Test barrel length: 24 Source(s): Accurate Powders [1] |
The .257 Roberts, also known as .257 Bob, [2] 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). [3]
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.
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". [4]
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. [5] Today, although surpassed in popularity by other cartridges, it lives on with bolt-action rifles being available from some major manufacturers.
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. [6] Neither unmodified .257 Roberts ammunition nor the original 6.5×50mm Arisaka ammunition are suitable for firing in rechambered Arisaka rifles. [7]
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.[ citation needed ] The original factory load for this is very similar to the .250-3000 Savage.
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. [4]
One of the common improvements is called the ".257 Roberts +P" which has a SAAMI maximum pressure limit of 58,000 psi (400 MPa) compared to the 54,000 psi (370 MPa) listed for the standard .257 Roberts. It is also the only rifle cartridge with an official "+P" designation. [8]
P.O. Ackley said that the .257 Roberts Ackley Improved was probably the most useful all-around cartridge. [9] 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.
Data below shows sample muzzle velocities and muzzle energies for a 61 cm (24 in) test barrel, except .250-3000 Savage, which is for a 56 cm (22 in) test barrel and .257 Weatherby Magnum, which is for a 66 cm (26 in) test barrel.
Cartridge | Bullet weight (g) | Bullet weight (gr) | Muzzle velocity (m/s) | Muzzle velocity (ft/s) | Muzzle energy (J) | Muzzle energy (ft·lbf) |
---|---|---|---|---|---|---|
.250-3000 Savage [10] | 6.5 g | 100 gr | 887 m/s | 2,911 ft/s | 2,552 J | 1,882 ft⋅lbf |
.257 Roberts [1] | 6.5 g | 100 gr | 920 m/s | 3,020 ft/s | 2,746 J | 2,025 ft⋅lbf |
.257 Roberts +P [1] | 6.5 g | 100 gr | 940 m/s | 3,090 ft/s | 2,870 J | 2,120 ft⋅lbf |
.257 Roberts Ackley Improved [11] | 6.5 g | 100 gr | 983 m/s | 3,226 ft/s | 3,133 J | 2,311 ft⋅lbf |
.25 WSSM [1] | 6.5 g | 100 gr | 1,010 m/s | 3,313 ft/s | 3,305 J | 2,438 ft⋅lbf |
.25-06 Remington [1] | 6.5 g | 100 gr | 1,013 m/s | 3,324 ft/s | 3,327 J | 2,454 ft⋅lbf |
.257 Weatherby Magnum [1] | 6.5 g | 100 gr | 1,070 m/s | 3,512 ft/s | 3,714 J | 2,739 ft⋅lbf |
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 models include the Type 38 chambered for the 6.5×50mmSR Type 38 cartridge, and the Type 99 chambered for the 7.7×58mm Type 99 cartridge, which is comparable in power to a modern .308 Winchester round.
A wildcat cartridge, often shortened to wildcat, is a custom cartridge for which ammunition and/or firearms are not mass-produced. These cartridges are often created in order to optimize a certain performance characteristic of an existing commercial cartridge, or may merely be intended as novelty items.
The 7×57mm Mauser is a first-generation smokeless powder rimless bottlenecked rifle cartridge. It was developed by Paul Mauser of the Mauser company in 1892 and adopted as a military cartridge by Spain in 1893. It was subsequently adopted by several other countries as the standard military cartridge, and although now obsolete as a military cartridge, it remains in widespread international use as a sporting round. The 7×57 Mauser was a popular stalking cartridge and sporting rifles in this chambering were made by the famous British riflemakers, such as John Rigby, Holland and Holland, Westley Richards and others. British cartridge nomenclature designated caliber in inches, and the cartridge was known as the .275 bore after the measurement of a 7 mm rifle's bore across the lands.
6.5 × 55mm Swedish, also known simply as 6.5×55mm, or in its native military as 6,5 mm patron m/94, meaning "6.5 mm cartridge model 1894", is a first-generation smokeless powder rimless bottlenecked rifle cartridge. It was introduced in the 1890s, and is still one of the most common cartridges in modern rifles built for the Scandinavian market today. The cartridge was developed in a joint Norwegian and Swedish effort starting in 1891 for use in the new service rifles then under consideration by the United Kingdoms of Sweden and Norway. In 1893, the cartridge was standardized and adopted under the name 6.5×55mm to facilitate logistical cooperation between Norway and Sweden. The two nations had independent armies and consequently the normal procedure at the time was for their respective governments to use the same ammunition and then purchase small arms of their choice. Norway adopted the Krag–Jørgensen M/1894 rifle, while Sweden adopted the Mauser m/1896 rifle design that was based on a Mauser service rifle designed around the 7×57mm Mauser cartridge.
The .243 Winchester (6×52mm) is a popular sporting rifle cartridge. Developed as a versatile short action cartridge to hunt both medium game and small game alike, it "took whitetail hunting by storm" when introduced in 1955, and remains one of the most popular whitetail deer cartridges. It is also commonly used for harvesting blacktail deer, pronghorns and mule deer with heavier rounds, and is equally suited to varmint hunting with lighter rounds. The .243 is based on a necked down .308 Winchester, introduced only three years earlier. Expanding monolithic copper bullets of approximately 80 to 85 grains or traditional lead rounds of 90 to 105 grains with controlled expansion designs are best suited for hunting medium game, while lighter rounds are intended for varmints.
The .375 Remington Ultra Magnum, also known as the .375 RUM is a .375 rifle cartridge introduced by Remington Arms in 2000. The cartridge is intended for large and dangerous game.
Considered by many as the most balanced of the "quarter bores" for hunting medium-sized game, the .25-06 Remington remained in obscurity as a wildcat cartridge for nearly half a century before being standardized by Remington in 1969.
The 7mm-08 Remington is a rifle cartridge that is almost a direct copy of a wildcat cartridge developed around 1958 known as the 7mm/308. As these names would suggest, it is the .308 Winchester case necked down to accept 7 mm (.284) bullets with a small increase in case length. Of cartridges based upon the .308, it is the second most popular behind only the .243 Winchester. However, the .308 is more popular than both. In 1980, the Remington Arms company popularized the cartridge by applying its own name and offering it as a chambering for their Model 788 and Model 700 rifles, along with a limited-run series within their Model 7600 pump-action rifles during the early 2000s.
The .257 Weatherby Magnum is a .257 caliber (6.53 mm) belted bottlenecked cartridge. It is one of the original standard length magnums developed by shortening the .375 H&H Magnum case to approx. 2.5 in (64 mm). Of the cartridges developed by Roy Weatherby, the .257 Weatherby Magnum was known to have been his favorite, and the cartridge currently ranks third in Weatherby cartridge sales, after the .30-378 Weatherby Magnum and the .300 Weatherby Magnum.
The .300 Winchester Magnum is a belted, bottlenecked Magnum rifle cartridge that was introduced by the Winchester Repeating Arms Company in 1963. The .300 Winchester Magnum is a magnum cartridge designed to fit in a standard rifle action. It is based on the .375 H&H Magnum, which has been blown out, shortened, and necked down to accept a .30 caliber (7.62 mm) bullet.
The 8mm Remington Magnum belted rifle cartridge was introduced by Remington Arms Company in 1978 as a new chambering for the model 700 BDL rifle. The 8mm Remington Magnum's parent case is the .375 H&H Magnum. It is a very long and powerful cartridge that cannot be used in standard length actions, such as those that accommodate the .30-06 Springfield.
The .264 Winchester Magnum is a belted, bottlenecked rifle cartridge. Except for the .244 H&H Magnum and .257 Weatherby Magnum, it is the smallest caliber factory cartridge derived from the 2.85 in (72 mm) Holland & Holland belted magnum case. It was introduced in the late 1950s and early 1960s with the .338 Winchester Magnum and the .458 Winchester Magnum as one of a family of short-cased 2.5 in (64 mm) belted magnum cartridges developed by Winchester based on the .375 Holland & Holland parent case. It was officially introduced to the public by Winchester in 1959. After many years of dwindling use it began enjoying a mild resurgence in popularity in the mid-2000s among long range rifle enthusiasts and reloaders due to the high ballistic coefficient of the heavier 6.5mm bullets and increasing popularity of cartridges such as 6.5mm Creedmoor, .260 Remington, 6.5 Grendel, benchrest and wildcat cartridges in 6.5mm.
The .260 Remington cartridge was introduced by Remington in 1997. Many wildcat cartridges based on the .308 Winchester case had existed for years before Remington standardized this round.
The .270 Weatherby Magnum was the first belted magnum based on the .300 H&H Magnum to be developed by Roy Weatherby in 1943. The cartridge is short enough to function in standard-length long actions with a brass length of 2.549" or 64.74mm and an overall length of about 3.295".
The .250-3000 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 Arms, and the fact that the original load achieved a 3,000 ft/s (910 m/s) velocity with an 87 grain bullet.
The .284 Winchester is a firearm cartridge, introduced by Winchester in 1963.
Parker Otto Ackley 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 existing firearms, and fireforming the ammunition to decrease body taper and increase shoulder angle, resulting in a higher case capacity. Ackley improved not only standard cartridges, but also other popular wildcats, and was the first to create a .17 caliber (4.5 mm) centerfire cartridge.
The 6.5mm Creedmoor (6.5×48 mm), designated 6.5 Creedmoor by SAAMI, 6.5 Creedmoor by the C.I.P. or 6.5 CM or 6.5 CRDMR for short, is a centerfire rifle cartridge introduced by Hornady in 2007. It was developed by Hornady senior ballistics scientist Dave Emary in partnership with Dennis DeMille, the vice-president of product development at Creedmoor Sports, hence the name. The cartridge is a necked-down modification of the .30 Thompson Center.
.30-06 Springfield wildcat cartridges are cartridges developed from a 30-06 Springfield "parent cartridge" through narrowing or widening the cartridge neck to fit a smaller or larger bullet in an attempt to improve performance in specific areas. Such wildcat cartridges are not standardized with recognized small arms standardization bodies like the SAAMI and the CIP.
The .280 Ackley Improved was the result of the .280 Remington case modification by P.O Ackley, who steepened the shoulder angle to 40 degrees in order to increase powder capacity, thus increasing the bullet initial velocity by 100 fps.