Help with Ladder Test Results

Discussion in 'Reloading' started by tlk, Oct 22, 2010.

  1. tlk

    tlk Well-Known Member

    Apr 11, 2008
    Trying to perform a ladder test on my rifle. Stats:
    CCI Primer
    H4350, 53 - 58 grains
    165 SGK, bt (not the crimped hollowpoint)
    Fixed 10X scope.

    Here is what I got at 300 yards, 70 degrees, no wind:


    Biggest thing I can see here is that the rifle doesn't really like the upper range of this selection, but between 57.0 - 53.5 grains there isn't a whole lot of difference - other than the the 57.0 grain shot, everything else falls into a 1.5" group. 54 and 56 grain sets are absolutely great, like crazy great. Can anyone shed some more light on this?

    The next day I stepped back to 600 yards, here is what I got. Wind 10 with gusts from the 4:30, temp 80

    The upper ranges are again not good (so far off they couldn't make the paper). But again I get this group where the charges are all over the map. So what I did was graph them veritically on the side. Left to right, they are 53.0 - 53.7, 54.0 - 54.7, 55.0 - 55.7, 56.0 - 56.7 (that makes the four straight lines, 53, 54, 55, 56).

    When I look at those lines I see that the 55 grain set is the tighetest with a 3 1/8" total vertical spread. The 56 grain set grouped second tightest, but the spread between 65.3 and 65.7 is 1.25". The 54 grain set sucked and did not do anything like the 300 yard target - but the tightest three of that group fell into just below 2".

    The 600 target shows me too that the 55.0 and 56.0 are falling low and out of the group, I think because of a cooler bore (shoot four, travel to the target, mark the target, travel back). Time between all shots was pretty consistent. The fact that the 53 and 54 grain groups had low shots that were NOT the 53.0 ad 54.0 shots kind of throws that out the window (I think).

    BUT - if you look at the 300 yard target I cant tell how these two targets correlate, other than the tightest overall group consistently is the 56.0 - 56.7 grain group.

    I need help here - what do you guys think? What is this test showing me? Everything is grouping in a way that I really cannot tell what is going on other than my loads of 58 grains are not what I should be shooting with this combo - it should be somewhere within this data set.

    Where do I go from here?

    Thankd for your help with this - it is greatly appreciated.
  2. Mikecr

    Mikecr Well-Known Member

    Aug 10, 2003
    What was the shot rate & velocities?
    Have you determined best seating depth on these bullets yet?
  3. kcebcj

    kcebcj Well-Known Member

    Jan 28, 2008
    I shot a ladder about a week ago at 300 yards with a 30-06 using a 165gr Accubond and IMR 4350 starting at 53gr and at 1/2 gr increments up to 57gr. It was very similar to yours and could make no sense of it.

    Very interested in what some of the more experienced shooters would conclude.
  4. tlk

    tlk Well-Known Member

    Apr 11, 2008
    I did not put them through my chrony - I have suspisions that it is lying to me based on a couple of other load tests. I am trying to get ahold of another to verify it.

    The details, for both the 300 and 600 yard sessions:

    Shot rate: every 3 mins, minimum time span, most were more. Barrel was not allowed to get beyond warm (i.e., no where near hot, closer to first shot warm).

    Best Seating depth is at 0.002" off of the lands. Seems to be best here.
    Lapua brass, fireformed, slight crush fit to chamber
    Case mouth sized at 0.02 under caliber, confirmed with pin guage.
    Case neck turned to 0.014, all consistent.
    Cases were in second firing off of annealing
    Brass OAL was consistent
    Brass cleaned with ultrasonic cleaner - insides were mirror clean
    Flasholes deburred
    Primer pockets uniformed
    Case mouths with VLD chamfer
    Bullets were all measured and matched in bearing surface - all same to within 0.0005 (using dial caliper)
    cartridge length at bullet ogive was within 0.001 of being the same (that took a LONG time, lots of slow work there)
    Powder charges were measured with a tuned Ohaus 5 beam scale. Was verified with scale weights at multiple points in reloading the 20 shots.

    I cannot figure out why I am not getting that cool stringing everyone shows, just a group of shots. At 600 it is only then beginning to show some relevance to the powder charge, but I still have groups that are intersecting - a lot. I spent some serious time on the ammo to take out all the "noise" that I could.

    Last edited: Oct 22, 2010