Ladder test target, and how to interpit it

Discussion in 'Reloading' started by abinok, Apr 3, 2005.

  1. abinok

    abinok Writers Guild

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    I finially got a chance to shoot the ladder test with my 300WM that I have been waiting to shoot for a month or so. This test was shot following the setup that is detailed in the ladder test document i have sent to several members here at LRH, with a couple of exceptions.
    This test was shot using 220SMKs, and H4831sc, a combo I have used before. What I changed was the seating length, going from .a 3.411" (3.828 on the SP gauge) to a 3.538" (3.955" on the SP gauge). The shorter is a load that I setup to fit in the magazine of my rifle. I started at 65.8gr of powder because I already know that there is another node below this at the shorter length, and because I know this load at this length is safe in my rifle..... no need to waste powder and bullets checking.
    It was about 10 minutes before sunset when I was ready to squeeze the trigger the first time, so, as expected, the chrony was blind to the bullets screaming overhead.
    I also borrowed the video camera from my brother in law, and set it up about 20 feet from the target at about a 45 degree angle. The camera makes it easier for me to concentrate on breaking the shot, not peering through the spotting scope to find the new bullet hole. its a superior metod compared to using shoot N see targets if you can controll the conditions (as in, not shooting the camera, and not having others around who will shoot it for you.
    Here is the layout of the test,
    [​IMG]
    collums are, order of shots, powder weight, Bearing surface length, Expected velocity, actual velocity, and notes.
    I used a .3gr step because of the case volume, and I specified the BS length because these are the "oddball" lengths from the sorted bullets. All bullets were uniformed with the meplat uniformer i made myself. If you missed it its over in the bullets and ballistics forum.
    Below the rows and colums, is a diagram of my ammo box, and where each round is in the box. Os mean loaded rounds in the box that ae not part of the test.... in this case, the rounds this load will replace, 220SMKs over 73grs of H1000. the Xs are empty spaces. This layout helps me keep track of where I am in the test.
    Here is the target.
    [​IMG]
    The numbers are from the left most column. Notice there is no #3. The first two rounds hit where I wanted them, so I didn't need to shoot it. Rounds 1, and 2 were for adjusting the POI and fouling the barrel. After I saw where #2 landed, I decided to exclude #3.
    The first thig you will nottice is that there are basically 2 groups, and that the top one is to the left of the lower one. the wind was dying down as the sun went down, so the latter shots did not need the full correction I had applied at the beginning of the test, so they moved left. Further, the horizontal spread is also due to the variation of wind speed. 1mph equates to .5inches of deflection with this load, at this range.

    Ill let all of you who are interested take a look at the target, and get some idea where you think you would find the most accurate load before I post back with where I think it is, and what the groups I shot for conformation look like.
    I have always been a promoter of the ladder test method of load development, and I believe there is no better way of working up a load.
     
  2. 257speed

    257speed Well-Known Member

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    I have never seen this before, would you be willing to e-mail a copy of how it works and how to do it, Please.
     

  3. ricka0

    ricka0 Well-Known Member

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    Re: Ladder test target, and how to interpret it

    Check out what Toby Bradshaw writes on Load Build

    After that, I use the technique LynnD uses to find a mode. Note when I do this I have a Std-Dev column too. (which is really required) and maybe an extreme Spread.
     
  4. royinidaho

    royinidaho Writers Guild

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    Re: Ladder test target, and how to interpret it

    Your process on the other thread sounded interesting. Tried it with a 223 HK SL 8 that we were trying to figure out.

    Our target was too close @100 yds to see any verticle dispersion but was able in 20 shots to settle on the load for that particular bullet. Thus, for us it worked.

    Just got a 375 H&H and figure that anything that will reduce the number of shots to find "the" load is a benefit. Will be giving it a go one of these first days.

    I can only see one 3 shot sequence that looks like a potential "Load", <font color="blue"> if I were doing the shooting</font> that's shots 5, 6 &amp; 7. If I don't really concentrate I string 'em up and down in that pattern.

    BTW is there a prize for the one that pick's em out. /ubbthreads/images/graemlins/smirk.gif
     
  5. 4ked Horn

    4ked Horn Writers Guild

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    Thanks abinok. I am going to say that load #13 is the load of choice because there is a pattern seen in loads 11 thru 15. 13 is in the center of that pattern. The pattern is a jump up from 11 to 12 then a slight decension from 12 to 13 to 14 then another jump up from 14 to 15. The pattern is a morror image of it's self with 13 being in the center of the image. This would show a harmonic tuning in and back out of the influences you wrote about in the email.

    My vote is for 13.
     
  6. 257speed

    257speed Well-Known Member

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    Got the e-mail, thanks
     
  7. Brent

    Brent Well-Known Member

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    If those were your actual MV's and not just what you predicted I would be checking out and loading for 2660-2720 fps and see if the wind changing spread the group wide and the #10 shot was a fluke hitting high like that. 2680-2700 seems to be the target and would offer the most resiliancy.

    If that didn't work out I'd load for 2600 fps or maybe try another powder.

    BTW, how far away was the target? 300 yards?
     
  8. dbhostler

    dbhostler Well-Known Member

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    I would run 67.8,67.9,68.0 and 68.2 check for ES and SD. If the velocity is what you want, go with it.
    db
     
  9. abinok

    abinok Writers Guild

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    [ QUOTE ]
    257speed
    I have never seen this before, would you be willing to e-mail a copy of how it works and how to do it, Please.

    [/ QUOTE ]
    Mine is a little different from that that toby describes. In this case I used .3gr. I can email mine if you like.

    [ QUOTE ]
    b1g_bore
    Note when I do this I have a Std-Dev column too. (which is really required) and maybe an extreme Spread.

    [/ QUOTE ]
    I usually measure for ES when I shoot my "confirmation" groups to pick the charge from the node. Its kinda hard to get ES or SD from one round /ubbthreads/images/graemlins/grin.gif

    Roy in Idaho, did you use my method?
    [ QUOTE ]
    BTW is there a prize for the one that pick's em out.

    [/ QUOTE ]
    Yes there is, and it goes to Jimm. the prize is a years supply of ammo in your favorite caliber. Jimm, you have 10 seconds to reply. /ubbthreads/images/graemlins/grin.gif

    [ QUOTE ]
    4ked
    Thanks abinok. I am going to say that load #13 is the load of choice because there is a pattern seen in loads 11 thru 15. 13 is in the center of that pattern. The pattern is a jump up from 11 to 12 then a slight decension from 12 to 13 to 14 then another jump up from 14 to 15. The pattern is a morror image of it's self with 13 being in the center of the image. This would show a harmonic tuning in and back out of the influences you wrote about in the email.

    [/ QUOTE ]
    Exactly! maybe I should give a second prize.....

    [ QUOTE ]
    Brent

    If those were your actual MV's and not just what you predicted I would be checking out and loading for 2660-2720 fps and see if the wind changing spread the group wide and the #10 shot was a fluke hitting high like that. 2680-2700 seems to be the target and would offer the most resiliancy.

    If that didn't work out I'd load for 2600 fps or maybe try another powder.

    BTW, how far away was the target? 300 yards?

    [/ QUOTE ]
    Brent, I wish I could have had the chrony up and running... just too late in the day /ubbthreads/images/graemlins/mad.gif Its interesting you point out the velocity window. My previous load was 73gr of H1000 at 2690. I was hoping to move up the velocity scale with the faster powder, and I did a little. Yes the target was shot at 300yds. I usually shoot my "confirmation" targets at 400, but decided to shoot these at 300 as well, just so yall can compare all the targets to each other more easily.
    Any way, enough suspense here's the target.
    Top row is the #12 load
    second row is the #13 load
    third row is the #14 load
    [​IMG]
    The average velocity of the six shots was 2741fps
    I don't put a lot of emphasis on SD, but ES was 14fps
    Groups for the #13 load measure .636ctc, and .437ctc
    I decided to post this ladder test instead of the other two I still have all the targets for because it just happens that the best load seems to be smack where the theory says it should be. If only it were always that simple!!!
     
  10. royinidaho

    royinidaho Writers Guild

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    Looked at this till my eyes went crossed.

    Did some measuring, very rough of course...

    Let me know how close I am. It would be a good calibration of my "measurement" system.

    If the only difference between #s 1 &amp; 2 are elevation and wind then the wind is worth a bit over an inch.

    The lower group is kind of symetrical assuming hold for wind was spot on.

    Upper group is about 3.7" above the first. That's a big jump unless the target is well beyond 100 yds.

    Horzional dispersion of the upper group is about 2". That says the wind was having a decent affect on the process.


    If #s 10 &amp; 16 are thrown out due to some bullet defect or some other excuse such as flys, snakes, wife yellin' atcha etc., Vertical dispersion of the upper group is about 0.9"

    Within that 0.9" are shots 12, 13, &amp; 14 with a vertical dispersion of about 0.4" and they are consecutive shots.

    So my semi-emperical, swag is that somewhere around the powder weight of #13.

    Also if the velocities were "actual" there's room for more powder and there may be another "node" starting w/#16. Ya just gotta chase that velocity. Don't cha? HeHeHe

    That's my story and I'm sticking to it this time. /ubbthreads/images/graemlins/mad.gif
    /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/smile.gif
     
  11. royinidaho

    royinidaho Writers Guild

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    Well damn, I posted a bit late. Just my luck.

    Well at least I get to see the results.

    Thanks for the experience. Think its good.
     
  12. royinidaho

    royinidaho Writers Guild

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    Well pat me on the back. I'm thinkin I'm gettin' the hang of it.

    Yes, I did use the ladder method.

    Sorry it took so long for me to do my calcs, but I got a late start. Now ya probably think I cheated. But I have the photoshop and MapInfo GIS files to prove I did the work.

    Have a good evening and thanks again.
     
  13. abinok

    abinok Writers Guild

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    Holy moly Roy!
    photoshop and MapInfo GIS?
    maybe I should be more sophisticated... I just go Hmmmm..... then go load some more ammo. /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif
    Im glad to hear that you had some success with this method. Its one of those that isn't heard of very often, but its such a great tool!! Sure were dark days back when it took a box of bullets, and a pound of powder to find a load for the 300WM. Course, did the store still have the same lot of both when you went back a month later for more componets..... almost never. So its back to developing more loads.... Now I usually have a workable load in less than half that, and then chrony the rest as I shot them to establish an acurate average, and ES!
    I Love It!!!
     
  14. 4ked Horn

    4ked Horn Writers Guild

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    [ QUOTE ]
    Exactly! maybe I should give a second prize.....

    [/ QUOTE ]

    Yep, I'm "da man". My prize will be finding my load in less rounds when I order those fancy shmancy wildcat bullets thereby giving me more rounds to confirm drops and practice with.

    I would like you to post the other targets you mentioned with an explanation of which load you chose and why so if my ladder test dosen't come out as obvious as this one I will have an idea of how to read it. If it isn't too much trouble.

    Or better yet, I will post pictures of my first ladder test to get your advice on reading it. (It will be a while. My wallet has to reinflate it's self after our trip to shoot with the MOAG gang.)