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Thread: 100gr GS - IMR7828 - 3765fps

  1. #1

    Default 100gr GS - IMR7828 - 3765fps

    Our hunting season for rifle ends the 21st of Jan and I have a new load to try before it ends.

    There were no pressure signs using IMR7828 and a 100gr GS moving 3765fps, as you will see on the brass, group good enough for hunting and at 2 1/2" high at 100 gives highest point of +3.75" at 200yds, zero of 350yds point blank a 450yds hold on top of shoulders and good out to 550. This is one flat shooting cartridge for sure with the GS.





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  2. #2
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    Default wow

    As soon as I saw 100 grains and a velocity above 3500fps I was pretty sure it would be a 257 Wby Mag. I've been seriously looking at this cartridge for these exact reasons! No matter how you slice it though, that's a heck of a speed and very good accuracy. Nice!

    For future reference (if you don't mind) how many grains of 7828 and what barrel length? I was thinking I might stretch the barrel a bit when I order mine to do this round justice.

  3. #3

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    Quote Originally Posted by AKArcherdaddy View Post
    As soon as I saw 100 grains and a velocity above 3500fps I was pretty sure it would be a 257 Wby Mag. I've been seriously looking at this cartridge for these exact reasons! No matter how you slice it though, that's a heck of a speed and very good accuracy. Nice!

    For future reference (if you don't mind) how many grains of 7828 and what barrel length? I was thinking I might stretch the barrel a bit when I order mine to do this round justice.
    It is a 26" barrel and that is all that is needed for the powder capacity of the 257Wby cartridge. I should not give out the charge since a GS does not create pressure like other bullets do since the driving bands are all that touch the lands. If you have a conventional bullet or TSX start at 71grs IMR7828 and work up.
    A GUN WRITER NEEDS:
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  4. #4

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    That's really cookin' BT... I think you should seriously recondider it as a deer round though... it might cauterize the wound channel on the way through

    Too bad you don't have prairie dogs down there.. or do you

  5. #5

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    Quote Originally Posted by MontanaRifleman View Post
    That's really cookin' BT... I think you should seriously recondider it as a deer round though... it might cauterize the wound channel on the way through

    Too bad you don't have prairie dogs down there.. or do you
    I am glad I do not have prairie dogs down here because I would burn my barrel up on one shoot, because it would be like eating potato chips, you just can't eat one. After shooting one I would want to keep on shooting.

    Tomorrow morning I have to go do some counseling in Hattiesburg and I will pass by my shooting range. I will leave early and try one more load that has less than a grain more powder charge and and a OAL of 3.209" as apposed to the 3.200" that I shot today. I believe with the low pressures I am getting I will be close to 3800fps. With this new load if I get a group less than an inch, then I will have almost the bottom end of velocities and accuracy I got out of my 257-300Wby. This 257Wby is much more efficient than the 257-300Wby and preforming close to the velocities I was getting accuracy loads in the 257-300wby.
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  6. #6

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    The GS's will ensure less barrel wear just by their design. I certainly will not be shooting prairie dogs with this load moving this fast. I let the barrel get completely cold before the next shot. But what is so cool is that the GS's do not heat the barrel up as much as the TSX's or conventional bullets do. I had less time to wait between shots of as much as 33%.
    A GUN WRITER NEEDS:
    THE MIND OF A SCHOLAR
    THE HEART OF A CHILD
    THE HIDE OF A RHINOCEROS

  7. #7
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    Wink Get into a recovery program...

    ...before it's too late. BT, when you see your counselor tomorrow, be sure to tell him/her that you're hopelessly addicted to speed and please modify your treatment plan accordingly.

    Of course you know that I am joking, and I know that you are the counselor. I've always enjoyed your enthusiasm, and I am convinced that you will be the first human to break the speed of light with a rifle cartridge.

  8. #8

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    Very interesting BT.

    Keep the information coming as I enjoy hearing about all things .257 WM related.

  9. #9

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    Quote Originally Posted by Doc View Post
    ...before it's too late. BT, when you see your counselor tomorrow, be sure to tell him/her that you're hopelessly addicted to speed and please modify your treatment plan accordingly.

    Of course you know that I am joking, and I know that you are the counselor. I've always enjoyed your enthusiasm, and I am convinced that you will be the first human to break the speed of light with a rifle cartridge.
    Doc, you are to funny, I could not afford the counseling it would take to heal me of my addictions for guns and speed.
    A GUN WRITER NEEDS:
    THE MIND OF A SCHOLAR
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  10. #10

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    Quote Originally Posted by theONE73 View Post
    Very interesting BT.

    Keep the information coming as I enjoy hearing about all things .257 WM related.

    I could not contain myself so I went this even. I found where max was with the IMR7828. I also found that when I seat the bullet closer to the lands pressures can jump quick. I tried 3.209" this afternoon and pressures rose some. So I will be backing down to 3.200" and will try and settle some where between 3725fps and 3765fps which will even give me more accuracy I think, notice I said I think. Tomorrow I am also going to try the CCI 250 primer since today I use the Fed 215 primer. Finalizing my load will take a little more work but this is truly a hot rod for sure.
    A GUN WRITER NEEDS:
    THE MIND OF A SCHOLAR
    THE HEART OF A CHILD
    THE HIDE OF A RHINOCEROS

  11. #11

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    I checked out the GS web site, those GS bullets look like great all around performers. Have you used them before? How is their accuracy?

  12. #12

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    Quote Originally Posted by MontanaRifleman View Post
    I checked out the GS web site, those GS bullets look like great all around performers. Have you used them before? How is their accuracy?

    I have not used them on game, but my friend Jerry who I went on that last deer hunt with has been using them every since we in this country could get them. He says they kill like the TSX but fly much further, flatter and always faster with the same charge of powder. I saw a deer he killed with it while we were hunting last week and I was certainly impressed. As far as I was concerned his wound channel looked better than the TSX wound channel on the deer I killed. They are accurate. Here is a target Jerry shot and this is his hunting load. Now I am a 165fps faster than he is using the same powder and only a grain and a half more of IMR7828 and you saw my target.

    Jerry's target


    Here is what makes them such a performer in ballistics.
    http://www.gsgroup.co.za/hvbore.html

    I have 150gr GS's coming this Thursday and I will be at the range Friday to load them in my 30-06 and GS Custom published loads have them moving at 3150fps. If I can get 3050 - 3150fps or some where in between and accuracy consistently under and inch, it will become my dedicated bullet in my 06 and I will use it for everything including dangerous game.
    A GUN WRITER NEEDS:
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    THE HIDE OF A RHINOCEROS

  13. #13
    Member JoeJ's Avatar
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    I use to shoot the 257 Weatherby mainly using Norma MRP and H4831. I was averaging 100fps less than your load with 100 grain full house loads but found the best consistent accuracy to be in the mid 3,400 range. I preferred the 117 grain pill for hunting and found the best accuracy around the 3,078 to 3,112 range depending upon powder type. Early morning, no wind conditions I could shoot 1.5" 3 shot groups but the groups would open up with a hot barrel. I liked the caliber as a hunting/killing cartridge but had no use for it as a shooting cartridge, as the slim barrel heated up fast and groups went to hell in a hand basket. I had a friend who put on a stress relieved barrel, pillar bedded with G10 and his rifle consistently shot 1" or a little better 5 shot groups at 100 yards in early morning, no wind conditions and one could fire 30 or 40 rounds in the morning at different ranges testing different loads in a timely manner. Wasn't possible to do that with my factory Weatherby with the slim 26" barrel.

  14. #14

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    BT, I noticed the web site said they normally ship their bullets moly coated unless specified otherwise. Do you shoot the moly's?

  15. #15

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    Quote Originally Posted by MontanaRifleman View Post
    BT, I noticed the web site said they normally ship their bullets moly coated unless specified otherwise. Do you shoot the moly's?
    I shoot the moly, but it is not the moly like you and I and others use to spray on our bullets. Jerry has carried some of these bullets all year in his pocket and the stuff does not wear off. You have to take something hard and would have to scratch it off. I have had no build up of any kind in my barrel neither has Jerry. Of course if you don't want to use those you can get them with out it. It is not some kind of thick stuff like on Winchester bullets and others. Look on this link and look at the bullet he is using to drive through a barrel and you will see what I mean.

    http://www.gsgroup.co.za/hvbore.html
    A GUN WRITER NEEDS:
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    THE HEART OF A CHILD
    THE HIDE OF A RHINOCEROS

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