First Ladder Test - need help

Discussion in 'Reloading' started by live2huntmt, May 12, 2014.

  1. live2huntmt

    live2huntmt Well-Known Member

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    I tried my first ladder test today but did not get the results I expected. Can anyone please help me decipher my final product? Details:

    Tikka T3 300 WSM
    Norma Brass
    Fed GM215M
    180gr Accubonds
    H4350 from 60.0gr to 67.0gr in 1/2 grain increments (15 total shots)
    COAL 2.880

    Me velocities steadily climbed from 2,726fps to 3,058 fps, but my POI did not climb along with them.

    According to Quickload and the OBT tool, my barrel nodes should be @ 61.7gr & 66.8gr w/ a 24.32" barrel. These should be shots 4 and 14 on my target.

    20140512_210653.jpg
     
  2. Barrelnut

    Barrelnut Well-Known Member

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    First, 67.0gr seems a bit hot to me.
    Second, Have a look at the loads for the 4 shots above line 3 on the red sticker. That looks like a node to me.
     
  3. live2huntmt

    live2huntmt Well-Known Member

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    Yes...67.0gr is hot....probably 1/2 grain higher than I should have gone.

    The 4 shots you are looking at are not 4 consecutive powder charges....they are from bottom to top: 66.0, 63.0, 61.5, 61.0 ..... and I could not find my 64.0 gr hole...I think it fell into the 61.5gr hole.
     
  4. kcebcj

    kcebcj Well-Known Member

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    What was the target distance. I do my ladder test at 335 yards...eaiser to read.
     
  5. live2huntmt

    live2huntmt Well-Known Member

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    300 yards
     
  6. Dr. Vette

    Dr. Vette Well-Known Member

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    11-12 and 14-15 are where I would look.

    Despite what you might think the POI does not always rise with an increase in MV. I have plenty of ladders that show that it does not, and I've seen others on here as well that scatter as yours do.

    Good luck with your testing!
     
  7. live2huntmt

    live2huntmt Well-Known Member

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    Thank You very much for your input! I will try smaller powder increments around shots 11-12 & 14-15 and re-perform ladder tests.
     
  8. CB11WYO

    CB11WYO Well-Known Member

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    Yup 11-12 and 14-15 like Dr. says...
    None of my ladder tests ever string vertical with any sort of rhyme or reason, even at 300 plus yards :)

    And if your 14-15 loads seem too hot then I guess 11-12 are the winners...
    Good luck!
     
  9. DocB

    DocB Well-Known Member

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    OK, I've yet to do a ladder test. I'll be doing mine when I get home from AFG sometime in the future.

    I can see 11-12 and 14-15. But why not 3-4? Even though there is a bit of vertical stringing, is that separation what eliminates this group?

    Thought I'd ask while I had the chance.

    Thanks in advance,

    Doc
     
  10. Dr. Vette

    Dr. Vette Well-Known Member

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    If it were me, which it is not, this is what I would do.

    Make 3 rounds each of the charges for the 11, 12, 14 and 15. You can do 13 too if you want to see if there is more to the pattern. Now fire each in the OCW round-robin fashion at their own targets so you do 11-12-13-14-15 and then start over, using 5 targets labeled, of course, 11-12-13-14-15. You're looking for the node where the group of 3 really comes together, and it should be moderately obvious.

    Going in less than 0.5gr increments at this point is likely useless. You will probably do better to find the best group in the load sequence above and then work on seating depth.

    But, that's just how I would do it.
     
  11. Kennibear

    Kennibear Well-Known Member

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    Shot #13 is vertically in the same group as #14&#15. So just shy of #13 and no more than #15. That is where I would look. I would load in 0.1 grain increases from #13 to #14 at 3 rounds per 0.1 gr+ or 15 shots total. I would shoot three round groups at this point to see what they would do. I would shoot the groups separated on the target to eliminate any cross talk. #13+#14+#15 looks promising.

    KB
     
  12. justgoto

    justgoto Well-Known Member

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    What was the wind like?

    I would not go with any of the shots on the outer edges horizontally; unless there was strong, varying winds. Because unless wind, (or lack there of,) put those shots there, a vibration had.

    But I really would need to see each shot's velocity to make a determination. I have seen shots line up appearing to be a node, but the velocities varied 150fps... which would not be a node.
     
  13. Dr. Vette

    Dr. Vette Well-Known Member

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    In the loads he's talking about the 0.1gr you suggest is 0.15% variation from load to load. I don't think that is statistically enough difference between them and is way too many shots, especially if you are looking for a true node. I would suspect that a true node would show over approximately a whole 1.0gr in this rifle, with the center of the node being the best. For example, my 7mm Weatherby has a node from 74.5 to 75.5 all being MOA or less, and I load 75.0gr (which is about 0.5MOA) to minimize any effect of temperature and other variables.

    YMMV. :D
     
  14. Kennibear

    Kennibear Well-Known Member

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    Dr. Vette

    I see your line of thought. The bullet strikes on target are very random. By isolating one parameter- Vertical Dispersion from velocity variation- as opposed to two parameters, vertical and horizontal, the only three shots clustering on the target are #13, #14 and #15. Since the powder increases cause vertical dispersion because of velocity increases that parameter caught my attention. Of all the other shots- vertically- there are no more than two consecutive that display low (vertical) dispersion. Given that book max is already exceeded by the powder charge of #14, the cautious side of me would approach #14 from the lesser not greater charge.

    What is missing is the velocity of each shot. If the velocity shows a high delta (change) between #13, #14 and #15 yet low vertical dispersion that is where the node lies. If the velocity delta is low then it is meaningless and indicates that the powder charge has reached diminishing returns of velocity vs. pressure. Since #14 is about book max and the velocity/pressure curve flattens above 65Kpsi (i.e. the velocity remains constant while the pressure increases geometrically) with current powder technology that is possible.

    All that being said, if you compressed the target horizontally and just look at where the bullets struck vertically, only 13,14 &15 are grouped together. Any other three consecutive shots are random.

    KB