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Thread: Load data for 7x57 with 139/140 g bullets and IMR 4831 or 4350

  1. #1

    Load data for 7x57 with 139/140 g bullets and IMR 4831 or 4350

    I have recently taken ownership of a 1974 built Rigby 275 and am load data to work up a nice flat shooting load. In effect to replicate the original "Rigby 275" load of 140gn bullet at 2,800 fps.

    I have available imr 4831 or 4350.

    And if anybody has a set of dies for 7x57 pls let me know before I go and buy new.

    Thanks in advance.

  2. #2
    I have recently gone through a load work up using those exact same powders with a 140 grain bullet in my girlfriends custom FN 7x57. With either powder the spread between minimum and maximum is very small -like two to three grains. I think we settled on 48.5 grains of IMR 4350 (I have a lot of it) which -though I haven't chronographed it- should be in the neighborhood of 2700 fps from her 24" barrel. We FL resized, trimmed all to uniform length, and seated to recommended OAL before crimping. Just over half MOA average group for 5, three shot groups. Primers were Winchester because that's what the little lady brought...~Muir

  3. #3
    I believe the key to getting higher velocity in the 7x57 is to use Winchester cases as they have a slightly bigger case volume than other. I would go with IMR4350 to start with at least that is what I intend to do with mine as most of the data I have collected over the years suggests this is the best bet.

  4. #4
    The Hornady manual gives a 139gr 2700fps with a max load of IMR4350 at 48.3 grs in a 22" barrel, so Muir's load is right in the ball park.

  5. #5
    Quote Originally Posted by shooternz View Post
    The Hornady manual gives a 139gr 2700fps with a max load of IMR4350 at 48.3 grs in a 22" barrel, so Muir's load is right in the ball park.
    You might want to work up to the same load, about 48.0 grains, of 4831 ( depending on IMR, Hodgdon, or H-4831ssc ) with the 140-gr bullets to see about accuracy.
    4831 and RL-19 really are good with 154 and 160 grain bullets.

    If you can get the 145-gr Speer BTSP, it has less bearing surface than most 140-grainers, and can be driven just as fast. It is a very good bullet out of the 7mm-08, too.

    But what is 100 fps, anyway? A 140-gr bullet at the mild 2,660 or the Rigby 2,800 FPS shoot to the same place with the same effect.
    Last edited by Southern; 29-07-2015 at 17:23.

  6. #6
    Quote Originally Posted by BWH View Post
    I believe the key to getting higher velocity in the 7x57 is to use Winchester cases as they have a slightly bigger case volume than other.
    unfortunately despite bigger meaning larger volume for more powder it also means slightly lower pressures (and thus MV) for same charges and it often means thinner brass that can't take the pressures of higher charges required to get the MV up
    Stronger thicker brass is just as likely to produce good MV - Lapua is popular for this reason

    I find Norma is a good compromise as it is usually both bigger in volume but also has more resilience to pressure than Win or Rem brass which is softer (Win) and harder (Rem)
    RWS is also a good compromise for 7x57

  7. #7
    I'm loading 44gns of H4350 under a Sierra 140gn SPBT with a CCI BR2 primer - accuracy is excellent and the round has taken UK deer and African plains game at 50 -300 yards with nicely controlled expansion and minimal carcass damage. Cases are new S&B from a batch of 250 bought from Wilson & Wilson.

    I'll have to check my notes for the exact MV.

    Adam.
    Last edited by Adamant; 29-07-2015 at 17:25.

  8. #8
    Quote Originally Posted by bewsher500 View Post
    unfortunately despite bigger meaning larger volume for more powder it also means slightly lower pressures (and thus MV) for same charges and it often means thinner brass that can't take the pressures of higher charges required to get the MV up
    Stronger thicker brass is just as likely to produce good MV - Lapua is popular for this reason

    I find Norma is a good compromise as it is usually both bigger in volume but also has more resilience to pressure than Win or Rem brass which is softer (Win) and harder (Rem)
    RWS is also a good compromise for 7x57
    I believe the advantage is that you can use a greater charge because of the extra capacity so increasing velocity and is the only way you can get the higher velocities in 7x57. ( The Rigby ammo of the late 90's was all loaded with Winchester brass) However I have yet to work up loads in the Wincheter brass. I couldnt get the velocity in Norma brass, but am not an expert!

  9. #9
    HeymSR20 - out of interest can I ask what twist the Rigby has?
    Jim
    I never make the same mistake twice.

    I make it five or six times.

    Just to be sure.


  10. #10
    Quote Originally Posted by JockStalk View Post
    HeymSR20 - out of interest can I ask what twist the Rigby has?
    Jim
    Haven't a clue, but will take it out later and measure it. Built in 1974 though.

    Now measured it - 1 turn in 10", and the same twist rate as my 7x65R.
    Last edited by Heym SR20; 31-07-2015 at 14:14.

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