Skip to main content
Help Center Community Shop

difference tween .257's

jogun
hey guys and gals,,,,anyone help me with the difference
between .257 roberts,,.257 ackley,,,
and the .257 ackley improved ,,,
and their availability.


much thanks,
jogun

take a kid hunting,,,you'll have the best time of your life.
0

Comments

8 comments

Date Votes
  • Snellstrom
    The 257 Roberts is the original, if I remember correctly it was developed in the 1920's and Ned Roberts is credited with its inception. It is basically a 7x57 Mauser necked down. Ackley came along and "improved" this cartridge and dozens of others increasing the powder capacity by changing the shoulder angle ( typically 20 22 or 24 degrees) sometimes he moved the shoulder up as well. The cartridge is then referred to as the 257 Ackley Improved, some people shorten that to 257 Ackley. If you have a 257 Ackley Improved you can shoot factory 257 Roberts cartridges in it and it will fireform them to the "improved" dimensions. Hope this clears some of this up.
    [^]
    0
  • Tailgunner1954
    To add to the above, 257Roberts ammo can be purchased "over the counter", but the Ackley version (of any cartridge) must be handloaded as it is considered a wildcat.

    Whittemore
    Some guys like a mag full of lead, I still prefer one round to the head.
    0
  • GWNelson
    I think Ackley used a 40 degree shoulder. Handloaded, ti will shoot with the factory 25-06, with less powder. GW.
    0
  • Snellstrom
    GW Nelson you are right, sorry about the mis information I gave Ackley was known for taking the mundane 20 degree shoulder and making it a 40 degree. I have read that too that the 257 Ackley Improved will walk with the ballistics of the 25-06 and do it with less powder and recoil. Ackley also stated that the 257"AI" was the max case capacity for the .25 cal before you started wasting significant amounts of powder to gain any more FPS.
    0
  • tony2772
    THE 257 IMPROVED USES A 28 DEGREE SHOULDER NOT 40. IT ALSO USES ABOUT THE SAME GRAINS OF POWDER. I SHOOT THE 25-06 IN THE RUGER MKII HAND LOADED IT PUTS OUT 3228MV AT 50 GRAINS OF H4350 WITH A CCI BR2 PRIMER AND REM CASES 3/4 MOA. AND THIS CARTRIDGE IS EASILY AVAILABLE.[:)]
    0
  • tony2772
    REF KEN WATERS' PET LOADS FROM HAND LOADER EXPENSIVE BOOK BUT WORTH THE WEALTH OF KNOWLEDGE FOUND WITHIN.
    0
  • nononsense
    Tony,

    A couple of quick notes:

    - Please turn off your caps as it is considered to be yelling on the internet.

    - The original poster is asking about Ackley Improved not "improved", there is a difference.
    quote:hey guys and gals,,,,anyone help me with the difference
    between .257 roberts,,.257 ackley,,,
    and the .257 ackley improved ,,,
    and their availability.
    The Ackley or the Ackley Improved shoulder IS 40 degrees and can be formed by firing standard Roberts ammunition in the Ackley chamber. The 'improved' that you reference can be a 28 degree shoulder (RCBS version) or it can also be 30 degrees or 32 degree or 35 degrees or even 44 degrees. The standard reference is the set of books by Ackley "Handbook for Shooters and Reloaders Vol. 1 & 2".

    Hopefully this clears up the matter.

    Best of luck!
    0
  • Ray Boone
    Right, the 257 Ackley Improved has a 40 deg shoulder while the 257 RCBS Improved has a 28 deg shoulder. I don't have a 25-06, but I do have a 257 Robts, 257 AI, 257 Wby, and a 250 Sav being built. The velocities of the Robts with 100 grain bullets are matched by 115-117 grain bullets from the Ackley. With the factory barrel I got about 200 fps more with the Wby than from the Ackley, until I had a Donnelly 28" barrel installed. Now it pushes 120 grain bullets to 3400fps with NO signs of excessive pressure. However as I've aged, I seem to be less enthusiastic about velocity and if I get 2800 from the 250 Sav with a 19 or 20" barrel, it'll do everything I'd want it to.
    0

Please sign in to leave a comment.

Recent Activity