With a modern action and handloading, this cartridge is capable of markedly improved performance. If you are not certain about the chamber design in your rifle, we suggest consulting your gunsmith. Data for muzzle velocity and muzzle energy is for a 24" barrel, except .250-3000 Savage which is for a 22" barrel and .257 Weatherby Magnum which is for a 26" barrel. We're taking a look at what the Army's Elite Units are using for service rifles and what the future of SOCOM sniping looks like. With light bullets the .257 produces little recoil and has a flat trajectory suitable for varmint hunting. Ackley said that the .257 Roberts Ackley Improved was probably the most useful all-around cartridge. With a modern action and handloading, this cartridge is capable of markedly improved performance. The modified Roberts cases are sometimes known as 6.5×.257 Roberts, although the case headstamp may still indicate .257 Roberts. Seat the bullet well out into the rifling, so that it makes good contact with the lands when the cartridge is chambered. The bore diameter of the .257 Roberts is .250 inches (6.35 mm) making it a ".25"/6.35 mm caliber", not to be confused with the more well known 6.5 mm caliber which uses 6.7 mm/.264" bullets or the slightly less common 6mm caliber Which uses 6.1mm/ .243” bullets. P.O. All Rights Reserved. *To properly chamber a rifle for .257 Ackley Improved cartridges, a gunsmith must set the original barrel back about 0.004”. That’s still less than the typical 60,000 to 65,000 psi of comparable modern rifle cartridges. Select a light load of relatively fast powder (IMR4895 is great) from the standard .257 Roberts data. Handgun shotshells are more complicated than one might think. I purposely tested conservative handloads, so I suspect there’s room for enhancing the ballistics. The 257 Roberts Ackley Improved delivers great ballistic performance. Ackley, the modified 257 Roberts was likely the best improved round compared with the couple dozen or so factory cartridges he’d experimented with Ackley’s signature case modifications included reducing the body taper and increasing the shoulder angle—both significantly! When Remington decided to adopt it as a factory cartridge in 1934, the company made a few minor dimensional changes to preclude firing factory ammo in rifles chambered for the wildcat round. Chambered for 257 Roberts Ackley Improved is Not offered at this time. The .25-06 which holds another 8 or 9 grains of powder outperforms the .257 Ackley by about 200fps. 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 not the strong recoil of larger popular hunting calibers, such as the 7mm family and the popular .30-06.[3]. The other prominent version is the .257 RCBS Improved, which features a 28° shoulder. From its introduction until the appearance of more popular 6 mm cartridges such as .243 Winchester and 6mm Remington, it was a very popular general purpose cartridge. Remington introduced the commercial version of this popular wildcat as a low-pressure round. [4], 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.[8]. I was pleased with the ballistics, and I lost only one case. While there are several versions of .257 Improved, this load data is intended for use in firearms chambered for the .257 Roberts Ackley Improved (40° shoulder angle). I embarked on my .257 AI project almost by accident. He chose the 7x57mm Mauser case to modify and, reportedly, tested myriad configurations before settling on the “perfect” .25-caliber varmint and deer cartridge. Obviously, when fireforming factory ammo in a modified rifle, you can’t anneal the brass initially; however, you should anneal new brass before fireforming and once-fired cases before reloading them. Conversion of war-souvenir Japanese Arisaka rifles, Learn how and when to remove this template message, "Accurate Powder Reloading Data Guide, 5th ed", https://www.americanrifleman.org/articles/2013/7/19/a-classic-returns-in-257-bob/, The .257 Roberts (.257 Roberts +P) by Chuck Hawks, "SAAMI Velocity & Pressure Data: Centerfire Rifle", "Nosler Reloading Guide 7, 250-3000 Savage", "Nosler Reloading Guide 7, 257 Roberts Ackley Improved", .257 Roberts (257 Roberts +P) at The Reload Bench, https://en.wikipedia.org/w/index.php?title=.257_Roberts&oldid=976100834, Articles needing additional references from August 2015, All articles needing additional references, Creative Commons Attribution-ShareAlike License, .257 Roberts (+P), .257 Roberts Ackley Improved, This page was last edited on 1 September 2020, at 06:11. When handloading rifle cartridges with blackpowder, Allan suggests you should not approach it... By cleverly increasing the parent cartridge's powder capacity, the .30-06 Ackley Improved... Give a Gift   While thinning out my firearms inventory, I realized I could convert my Ruger Hawkeye bolt-action rifle chambered for .257 Roberts to .257 AI. The Remington part of the moniker was eventually dropped. Later, when I measured water capacities of a standard .257 Roberts case and several fireformed AI cases, the difference was about 13 percent (60 grains compared to 53 grains of water). However, an even more important feature of the typical Ackley Improved (AI) wildcat is that he maintained the shoulder headspace datum of the parent factory round. 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. James Tarr runs through the 3-Second Headshot drill. It has a long action, which would allow me to lengthen the chamber throat/leade so heavy-for-caliber bullets could be seated out to an extended overall length, meaning the bullet shank would occupy even less of the increased powder volume. The other prominent version is the .257 RCBS Improved, which features a 28° shoulder. I want to make readers aware of one special step that’s required when handloading the .257 AI. It also means you can easily fireform .257 Roberts factory brass or loaded rounds to achieve the .257 AI case shape, so you don’t need expensive forming dies or go through extensive case-forming steps. Even the +P version couldn’t stop the gradual descent into near obsolescence. Coincidentally, I had just embarked on my most recent handloading project with the interesting .257 Roberts Ackley Improved wildcat. To get started, click the link below to visit mymagnow.com and learn how to access your digital magazine.

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