Low ES and SD, but accuracy not there

Discussion in 'Reloading' started by goose, Oct 25, 2009.

  1. goose

    goose Well-Known Member

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    H1000 has been giving me great es and sd in my two rifles, 6mm remington and 7 rem mag. Yesterday, I shot a 5 shot group with the 6mm 50.8 of H1000 (95 gr Nbt) and got 3065 for shots 1-4 and 3057 for shot 5. I was very surprised that the chrony kept showing (dupl) on each shot till the last. My 7mm was not quite as steady, the last 3 shots of a 7 shot group were duplicate vel and the others not far off. Both loads are seated touching the lands or very close to it. Both rifles are shooting 1.5 to 2.2 inch groups and are capable of 1". I was thinking of seating farther off the lands next to see what happens. Any other ideas?
     
  2. phorwath

    phorwath Well-Known Member

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    Is your chronograph working properly? I've never recorded the same velocity 4 shots in a row on either of mine. Or even three shots in a row in my 7mm Rem Mags. So that sounds suspicious based on my experiences.

    Low ES and SD often coincides with good accuracy, but I've learned that there aren't any guarantees in this sport/hobby.
     

  3. Limbic

    Limbic Well-Known Member

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    I've gotten the same MV three times in a row for my 7mag, but only rarely. When I work up a load I pick a depth for a bullet then try different powder amounts. When I get a low ES/SD I begin to work with seating depths. In my 7 the Vld' like a bit of jump. .010 for the 180's and .080 for the 168's. Most other bullets like to jump as well. Barnes like .030. Anyway my 260 likes them on the lands.
    I think this method works well. Check out the article on load development.
     
  4. goose

    goose Well-Known Member

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    I shot a group today with the 7mag and 168vlds about .040 off the lands with the same results. No dupl mv, but similar numbers. 1.75 group. By the way, the rifle is a savage 116 weather warrior with accustock and brake. I think I will try a few at .080. If I can't get it to group well, should I go to a different powder?
     
  5. J E Custom

    J E Custom Well-Known Member

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    Goose.

    Normally when a load has good SDs and ESs It is a good powder, primer and case combo
    and you should try different seating depths for accuracy. If this does not work then try a
    different bullet of the same weight.

    Some barrels just don't like some bullets and you have to try others(Brands and even weights.

    J E CUSTOM
     
  6. LRHWAL

    LRHWAL Well-Known Member

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    I like a load with low ES to avoid stringing at longer ranges, so yes, this is really important.

    Accuracy though can have a lot to do with seating depth and "barrel timing". The whole oscillations and harmonics discussion. Try slightly different (safe) velocity ranges.
     
  7. canderson

    canderson Well-Known Member

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    You might try one of the 7mm 0.010 into the lands. If you can work the bolt and eject the cartrdige in one piece, it will work for hunting. My target rifle likes the 180's there. Use an OAL length gauge to get the 0.010. My rifle wil pull an unfired case with this little jam. Good Luck.
     
  8. mmmooretx

    mmmooretx Well-Known Member

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    You did not say whose bullets you are using. I have a 24" Kreiger barrel and the SGK 200 gr. like 0.010 off the lands, Barnes 180 gr. TTSX like 0.040 off the lands and I am going to try a load today or Sat., rain & work permitting of Berger 210 hunting VLDs at 0.005 off the lands. Both the Barnes and Sierra's are 0.43" groups at 100 yards with my 300 Win Mag. I hope to improve that too. I find that it is a strange blend of barrel dynamics to find the sweet spot of your gun/load for the right combination of powder and distance between the ogive/land. I found that it is easier to hold one constant and vary the other until you have the right combination. I also spent 30 minutes talking to the specialists at Sierra and they love talking guns, loads and thewill certanly help
     
  9. phorwath

    phorwath Well-Known Member

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    I shoot both 168 7mm and 210 308 Berger VLDs 0.010" into the lands in my 7mm Rem Mag and 300 Win Mag. VLD have a history of doing well jammed into the lands. I seem to achieve lower ES and SD there than off the lands and I speculate the back press against the lands may help get more consistent rates of powder ignition. Both loads are hunting loads. 0.5 moa or less out to the ranges I shoot. I load these single shot style and both loads will eject unfired rounds with the bullet intact. I do use a Hornady gauge on dial calipers to ensure the seating depth is within +/- 0.0006" simply for consistency purposes.
     
  10. Michael Eichele

    Michael Eichele Well-Known Member

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    Low ES's and SD's dont always equal accuracy. Barrel harmonics equal accuracy. You just need to find either a different powder and or powder charge (most likely the charge) and or a different bullet. As stated, seating depth helps too.
     
  11. Jamie6.5

    Jamie6.5 Well-Known Member

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    Yup! It's time for an OBT/OCW session at the range.
     
  12. goose

    goose Well-Known Member

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    I developed my load from a ladder test for OCW. As I have read, there were two "nodes" where POI and velocity were close. One was on the lower end of the charge weight, and this load was close to the top. I could try the lower charge weight, but my rifle only produces 2850 shooting the 168VLD with the 70gr load of H1000. I was hoping for more out of the 7mag, but the advertised 24" barrel length includes the muzzle brake, so it's really more like 22" from the bolt face to where the brake starts.

    I am using a lee collet die and not much neck tension, much less than my other rifles using FL sizing dies. Will that cause problems trying to edject a loaded round jammed into the lands?

    I should be able to shoot this weekend, will keep you posted.
     
  13. phorwath

    phorwath Well-Known Member

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    If the neck tension is too loose, the bullet can set back when it engages the lands, seating depth can change on any rounds in your magazine under recoil, and the bullet could pull out of the case mouth when you try to eject an unfired round. Try loading some rounds and ejecting the unfired cases and see if the bullet comes out with the case, with the muzzle pointed up. If they come out, then measure the seating depth again to see if it's changed from the initial setting. If all looks good, you may have enough neck tension. Also, take a loaded round and try to shove the bullet in deeper with your fingers. The bullet seating depth shouldn't change and the bullet shouldn't move. If it does you don't have enough neck tension for a hunting round.
     
  14. goose

    goose Well-Known Member

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    Finally got it to shoot with the 140 ballistic tips. I have a few rounds of factory ammo that shot well, tested that, and it shot .77" when everything else I tried did 1.5 to 2.5"

    I tried seating everywhere from jamed .016 to jumping .080 with the VLD's to no avail. I have a precision mic RCBS set and seated the ballistic tips to the same as the factory rounds. (over.100 jump) Finally it shot a nice .88 group with very little vertical.

    I haven't tried that with the VDL's I'm tired of load development and with less than a week to opening day, I need to get out and do field practice.

    Thanks for all the help.

    PS, the 6mm remington worked out with 50.5g of H1000 seating the 95gr ball tips with a little more jump as well. It's always good to have a backup rifle, 2 or 3 is even better.