.257 Roberts

Infobox Firearm Cartridge
name= .257 Roberts


caption=
origin= USA
type= Rifle
service=
used_by=
wars=
designer= Ned Roberts
design_date= 1920s
manufacturer= Remington Arms
production_date=1934-Present
number=
variants= .257 Roberts (+P), .257 Roberts Ackley Improved
is_SI_specs=
parent=7x57 Mauser
case_type=rimless bottlenecked [http://www.accuratepowder.com/data/PerCaliber2Guide/Rifle/Standarddata(Rifle)/257cal(6.55mm)/257%20Roberts%20(standard)%20pages%20215%20and%20216.pdf Cartridge info at Accurate Powder] ]
bullet=.257
neck=.290
shoulder=.430
base=.472
rim_dia=.473
rim_thick=
case_length=2.233
length=2.775
rifling=1-10"
primer=large rifle
is_SI_ballistics=
bw1=75
btype1=HP
vel1=3563
en1=2115
bw2=90
btype2=HPBT
vel2=3368
en2=2267
bw3=100
btype3=SPBT
vel3=3108
en3=2145
bw4=115
btype4=NOS PART
vel4=2777
en4=1970
bw5=
btype5=
vel5=
en5=
test_barrel_length=
balsrc= Hodgdon [http://data.hodgdon.com/cartridge_load.asp .257 Roberts data at Hodgdon] ]

The .257 Roberts a medium powered .25 caliber cartridge known affectionately as the "Bob". It has been described as the best compromise between the low recoil and flat trajectory of smaller calibers such as the .22 and 6mm, and the strong energy but strong recoil of larger popular hunting calibers, such as the 7mm family and the popular .30-06. [http://www.chuckhawks.com/subscribers/rifle_cartridge_page/257Rob.htm The .257 Roberts (.257 Roberts +P) by Chuck Hawks] (membership required)]

History

Many cartridge designers in the 1920s were creating various .25 caliber cartridges. Because of its size, the 7x57 Mauser case was a common choice, having near the ideal volume capacity for the "quarter-bore" (called this because the .25 caliber is one quarter of an inch) 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 made by Roberts, they called it the .257 Roberts.

From its introduction until the appearance of the popular 6mm cartridges (.243 Winchester and 6 mm Remington) it was a very popular general purpose cartridge. [http://www.chuckhawks.com/257Rob.htm The .257 Roberts by Chuck Hawks] ] Today though overshadowed by other cartridges, it lives on with bolt-action rifles being available from some major manufacturers.

One of the less well known but nonetheless common rifles commonly found chambered in .257 Roberts is the Japanese Type 38 Arisaka, which was often converted to the more readily available domestic cartridge due to the relative unavailability of commercially produced 6.5x50SR Japanese cartridges in post-WW2 America.Fact|date=September 2007

Performance

With light bullets the .257 produces little recoil and has a flat trajectory suitable for varmint hunting. With heavier bullets it 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 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 58,000 PSI compared to the 54,000 PSI listed for the standard .257 Roberts. [http://www.accuratepowder.com/data/PerCaliber2Guide/Rifle/Standarddata(Rifle)/257cal(6.55mm)/257%20roberts+%20P%20pages%20217%20and%20218.pdf .27 Roberts (+P) load data at Accurate Powder] ]

P.O. Ackley said that the .257 Roberts Ackley Improved was probably the most useful all-around cartridge.cite book
last = Ackley
first = P.O.
title = Handbook for Shooters & Reloaders
series = vol I
origyear =
year = 1962
publisher = Plaza Publishing
pages =
isbn = 978-9992948811] The Ackley Improved was a typical change of a steeper shoulder coupled with blown-out sides for more of a straight cartridge, providing greater powder capacity.

Comparison

* using a 26" barrel.

ee also

* List of rifle cartridges
* 6 mm caliber
* Delta L problem

References

* cite book
last = Barnes
first = Frank C.
editor = McPherson, M.L.
title = Cartridges of the World
edition = 11th Edition
origyear =
year = 2006
publisher = Gun Digest Books
location =
pages =
isbn = 0-89689-297-2

External links

* [http://www.reloadersnest.com/frontpage.asp?CaliberID=32 .257 Roberts at Reloaders Nest]
* [http://www.reloadbench.com/cartridges/257r.html .257 Roberts (257 Roberts +P) at The Reload Bench]