Can someone help me interpret these OCW results?

Discussion in 'Reloading' started by busse fan, Aug 13, 2013.

  1. busse fan

    busse fan Well-Known Member

    May 16, 2011
    Hi there. Kind of stumped here and hoping you can help me out. Working up a load for a 338 LM in a weatherby accumark. 1F lapua brass, cci 250 and H1000 with the 300gr OTM Berger. Loaded to 2.906" ogive which puts me 0.160 off the lands (3.066" ogive lands).

    I started with 3 shots 81, 82.6 and 84.2 which chonographed 2343fps, 2356fps and 2394fps respectively. Berger calls for 81gr @ 2500fps and 85.2gr @ 2629fps so I know right there that isn't going to happen.

    I'm not sure if you can read the charge weights on the picture I took but the charges top (orange targets) L to R are 85gr, 85.8gr, 86.6gr, 87.4gr, 88.2gr and 89gr.

    The bottom target first 3 are foulers where I just "threw" powder that was ~85gr. Continuing from L to R 89.8gr, 90.6gr, 91.4gr, 92.2gr (I held 2moa low as I was concerned it would go off the top of the paper. I drew a line where center would have been uncorrected. The 92.2gr load chronographed 2691, 2686, 2684fps.

    The primers on the 81gr and the 92.2gr load are BOTH flat and they look exactly the same. Brass is very easy to resize (barely touches the side of the brass, mostly shoulder and neck) and primer pockets are tight. I don't have any "pressure" signs to go by so not sure if I can keep going up.

    I would also appreciate any feed back on nodes you see and perhaps some advice on what to do next for further load development.


  2. Mikecr

    Mikecr Well-Known Member

    Aug 10, 2003
    I would load up ~50 rounds ~86gr for Berger's seating test.
    Then, load up ~30 with best seating & shoot a 300yd ladder.

    If you don't see something worth chasing you need another powder.
    Another ladder with same best seating and another powder.

  3. BountyHunter

    BountyHunter Writers Guild

    Jun 13, 2007
    A problem with the OCW is they forget the Chrono and MV. You will have tight MV variances between groups on a node and that is a very good way to confirm you are in a node.
  4. benchracer

    benchracer Well-Known Member

    Dec 18, 2009
    I would say that you have a node that starts at 88.2 and ends at 89.8. Note the increased vertical spread on both sides of the node, which is particularly pronounced with the 90.6 load. Also note the relavtive stability of the POI starting with 87.4 and continuing through 89.8 In that node, I would say that 89.0 is your load.

    It will also be interesting to see what kind of results you get as you go up from the end of this test. It looks to me like 92.2 may be the beginning of the next node, but without the following data points one can't know for sure. Note that at the end of the test vertical spread is starting to tighten and the POI remained stable in the last two groups.