7mm reload problems (ballistics)

Discussion in 'Reloading' started by retiredcpo, Jun 13, 2010.

  1. retiredcpo

    retiredcpo Well-Known Member

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    I have a load for my 7mm rem mag that shoots good
    but my velocity is reall low acording to the bc calulator on best of the west web site
    Im using 61 grains of rl 22 pushing 160 gr accubonds At 500 yards I have to come up 38 clicks. (9.2 Moa)
    according to the BC calc im running 2595 fps according to nosler load data I should be up aroun 3000 fps
    What am I missing here?
    I used the correct scope height but does a 20 moa base affect that?
    retiredcpo
     
  2. kiwi3006

    kiwi3006 Well-Known Member

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    What is your zero distance?
    What altitude are you shooting at?
    What was the temperature?

    Stu.
     

  3. retiredcpo

    retiredcpo Well-Known Member

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    Stu
    Sorry
    The gun is zeroed at 200 yards the alt is right at 2500 ft
    and it was 67 degrees out the time.
    I get one ragged hole at 200 with this load so I dont really want to change it but with the low speed comes bigger drop ect
    I am also leary of increasing the load accrding to my reload books and accurate the max load is 65 grs but according to nosler the max load is 63 gr two grain differance
    I really dont want to push the pressure to high
    retiredcpo
     
  4. kiwi3006

    kiwi3006 Well-Known Member

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    Using my ballistic programs I get exactly the same MV as you.

    For what it is worth I am using 72 gr H1000 with 160 accubond, federal brass, federal 215 primer, proj just on the lands, getting 3067 fps.

    Stu.
     
  5. Fitch

    Fitch Well-Known Member

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    I'm using 68.5g of RL25, Win Brass, 160g AB seated 0.020" off the lands, FED215, getting 3022 fps out of a 26" barrel (chronograph average for 6 shots) into 1/2 MOA. QuickLoad predicted 2999 fps, measured 3022.

    Fitch
     
    Last edited: Jun 14, 2010
  6. retiredcpo

    retiredcpo Well-Known Member

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    fitch
    thats what i3 bothering me about my load
    your load data is real close to the mv you are getting
    my load data says I should be up around 2963 allmost a 400 fps differance
     
  7. Fitch

    Fitch Well-Known Member

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    I have had similar experiences. With the 55g NBT load data for a .243Win I am about 400 fps under what Nosler predicts in their manual. Can't explain it. With other loads in their manual I'm right on.

    I bought QuickLoad as part of trying to understand that experience.

    Fitch
     
  8. ilscungilli

    ilscungilli Well-Known Member

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    The brass you use will have an impact on the amount of powder/pressure. I am using Norma brass, and relative to the Federal brass, I need to use one more grain to get equivalent velocity. With the 160 gr accubonds, I use 65 gr RL-22, CCI-250 primers. This gives 2950 FPS (24" barrel). My older Sierra manual lists 66 gr. of RL-22 as the max with the 160 gr. Jacketed Fail Safe, Rem cases, 9.5 M primers.
     
  9. retiredcpo

    retiredcpo Well-Known Member

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    The accuate web site lists the max RL22 load as 65 grains
    I was wanting to increase closer to 63 grains but I got a email from nosler with load data showing 63 grains as max
    So I not sure how much I can go I dont want to over presure this gun.
    any idea what one more grain would do to my MV?(62grains)
     
    Last edited: Jun 14, 2010
  10. ilscungilli

    ilscungilli Well-Known Member

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    For the components listed above (Norma, CCI-250, RL-22, etc), I was getting about 30 fps for each grain increment between 62-65 gr.
     
  11. retiredcpo

    retiredcpo Well-Known Member

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    guess I should add Im using winchester brass and winchester mag primers
    visigoth if I use your numbers a a rough estiment of 30 fps per grain there is no way im going to get this load up to 2900 fps or better
    guess Ill have to start to consider looking for a differant load
    sure dont want to this one shoots good its just slow
    I was messing with the balistic software and 2900 FPS is 2 moa better
     
  12. Gunpoor

    Gunpoor Well-Known Member

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    I have not loaded for the 7RM but have loaded for it's parent case, which is the 264Win. I believe if you are wanting more speed from your rifle you need to switch to a slower powder such a H1000 or Reloder 25. You can probably find more speed at lower pressure with slower burning prepellant. BTW, reloading data is a guide, and your own rifle will tell you what the top end for the components you are putting together. I have had some rifles that easily digested loads that exceeded book max and others that topped out at less than max. Also, I have a 30/06SPR. that shoots a slower velocity load so well that I don't even try to speed it up and have shot deer at 600 yds with it. If you know where to hold to hit at longer ranges you will be the only one who will know how fast or slow your bullets are going.
     
  13. retiredcpo

    retiredcpo Well-Known Member

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    gunpoor
    I tried H1000 and the groups were not good.
    I have not tried RL25.
    You are 100 percent correct this load shoots good so far (real good)
    but I really would like to gain 1 to 2 Moa out to 600 to fully accomplish what I am trying to get this rifle to do I would like the leupold varmit hunter reticle to work but im off by 100 yards
     
  14. retiredcpo

    retiredcpo Well-Known Member

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    I guess what Im trying to say is Im frustrated because I dint understand why Im about 400 fps slower than I should be
    100 fps or less I could understand but 400 fps is alot the way I see it.