338 ultra load development

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by YZEATER, May 22, 2011.

  1. YZEATER

    YZEATER Well-Known Member

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    started load testing for my new/used 338 ultra mag yesterday. didn't get anything better then about a 2.5" -3 "group.

    new cases, 250gr AB, retumbo , and H1000, started 2.0 grains less then max and increased in .5 grain increments. bullets were seated as long as the magazine box would allow. i didn't have any reloader 25 to try. the primers had some cratering, but were not flattened, and bolt lift never got hard on any round. did have one primer blow thru and ruin the case on the lowest H1000 load.

    gun is rem 700, muzzlebrake, 3.5 lb trigger, leupold 4.5 x 14 vxIII.

    i think i'll try some 225 AB and some reloader 25 with the 250's.

    i didn't resize the new cases, just primed and loaded them up. problem?
     
  2. Topshot

    Topshot Well-Known Member

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    That's not too good.

    What rifle is it? Standard factory Remington barrel or custom heavy barrel.
    A load of 93 to 95 grains of H1000 seated to 0.020" off the lands with a 250 grain AB should produce excellent accuracy without too much load developement work.

    Check you brake is tight and aligned properly to the bore.

    The scope or mounts could also be suspect.
     

  3. YZEATER

    YZEATER Well-Known Member

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    standard remington 700 light 26" barrel. going with hodgdon's loading of 98.0 max i started with 96.5 and went up in .5 gr till max.

    i redid the mounts as i was going to change them out, but didn't have what i thought i had on hand so everything was cleaned and remounted. scope is 1 season old, and shot great on my 257 wthby.

    brake is tight but i don't have a way to check alignment.
     
  4. Topshot

    Topshot Well-Known Member

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    Try 95 grains of H1000. If still no good and you are not happy with the accuracy. Take it to a gun smith. Let him sort out the problem.

    With the high cost of .338 RUM ammo it is no use mucking about with a rifle that is not accurate. It may cost you a bit to get a gunsmith to sort out your problem, but at the end of the day you will have a much better rifle and far less frustration.
     
  5. YZEATER

    YZEATER Well-Known Member

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    I forgot my factory loaded ammo when i left so i didn't have a baseline to start from. The barrel was clean and according to the previous owner it only had 22 rounds through it.
     
  6. Long Time Long Ranger

    Long Time Long Ranger Well-Known Member

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    Uniform primer pockets and turn your necks. Freefloat your barrel.
     
  7. YZEATER

    YZEATER Well-Known Member

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    Oops. Forgot to mention i did uniform the primer pockets before loading.

    I've never turned necks before.

    I have a synthetic stock but never did check if it was floated. After there first group i did make sure to rest the gun just ahead of the chamber.
     
    Last edited: May 22, 2011
  8. Franklin

    Franklin Well-Known Member

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    If the stock is the factory tuppeware p.o.s, I would round file that thing and get a good synthetic or laminate. You will do nothing but fight that stock, no matter what you do to it!
     
  9. orangeride

    orangeride Well-Known Member

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    Ditch that stock. I built two matching .338 rums with 27" heavy krieggers. My rifle I used a hs stock and it shot 1/2" the first time out with 225 nab. My buddie was to cheap and wanted to use the factory stock. We never could get it to shoot till we got rid of it. I do think the factory laminated is pretty good if it's bedded and floated right. But it's heavy.
     
  10. sp6x6

    sp6x6 Well-Known Member

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    Sounded as if your brass was brand new, my new brass runs short in the chamber, and I dont accuracy load until second firing. Mine is 5-6 thousands short
     
  11. YZEATER

    YZEATER Well-Known Member

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    The brass was brand new.

    Yup it has the factory Remington synthetic stock.
    What's a good replacement? I'd rather have a lightweight syn.
     
  12. Long Time Long Ranger

    Long Time Long Ranger Well-Known Member

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    The 250 AB's are usually very accurate. Could be your rifle just doesn't like them. Some rifles just don't like a bullet and love another. My rifle is just like yous with the factory stock and is a very accurate long range rifle. I shoot the 225 AB's with 99 grains of RE-25.
     
  13. 338 bruce

    338 bruce Well-Known Member

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    My remington sendaro 338 rum liked any bullet tested. I had to send it back for repair and remington replaced the barrel. The new barrel wouldnt shoot any bullet with a with a short bearing surface (225-250 boat tails of any brand). I switched to a hornady 250 flatbase and my accuracy came back. Both barrels shot the 300 smk very well.
     
  14. fatrack

    fatrack Well-Known Member

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    I'm surprised nobody caught it but in my opinion your problem is you never sized your new brass. Have a look at the necks on new brass right out of the bag, its all jacked up and you will never get consistant neck tension unless it is sized (thus no accuracy).