OCW Test results: interpretations welcome

Discussion in 'Reloading' started by zoeper, Apr 26, 2008.

  1. zoeper

    zoeper Well-Known Member

    Feb 20, 2008
    Hi Guys,

    I followed Dan Newbury’s OCW Method to the letter and chose 7 charges to test, but although the visual picture seems to indicate something, using the average POI of each group as suggested, reveals that the average POI’s all print within a 0.68” group at 110 yards (if you exclude the 5th group that is 0.4” at 110 yards)
    Looking at the targets from left to right the group sizes and average POI for each group reads as follows:
    #1 – 43.5 Grains 0.375” group X1.05, Y0.84
    #2 – 43.7 Grains 0.794” group X0.92, Y0.84
    #3 – 43.9 Grains 0.778” group X1.04, Y1.07
    #4 – 44.1 Grains 1.198” group X1.11, Y1.10
    #5 – 44.3 Grains 1.701” group X1.48, Y1.23
    #6 – 44.5 Grains 1.509” group X0.91, Y1.05
    #7 – 44.7 Grains 1.625” group X1.23, Y0.80

    I cannot see the average POI following any noticeable trend, however the groups do tend to open up as the loads gets bigger. From the results it also seems that I might benefit from starting a couple of charges lower.
    Unfortunately I could not get hold of a chronograph for this test and cannot tell you the velocities achieved in the test.
    Cal: .243 Win
    Bullet: Hornady 87gr hpbt
    Brass: Remington, fired once before and neck sized only for this load.
    Powder: Somchem 365 (comparable to IMR4350 or AR2209 or H205)
    Primer: PMP Magnum large rifle
    Rifle: Steyer Manlicher L with 22” barrel
    Average POI for each group was determined by adding all the x values for that group and dividing by 3 and all the y values and dividing by 3 (3 shot groups)
    Group sizes were calculated using Point Blank software.

    Would anyone care to give me their 2 cents worth on these results?

  2. royinidaho

    royinidaho Writers Guild

    Jan 20, 2004

    I'm not familiar with your rifle composition such as barrel weight, bedding, free float/pressure point etc.

    maximum X spread is about 0.57
    maximum Y spread is about 0.43

    Nothing wrong with that!

    Group size spread is about 1.3 inches with the lowest powder weight giving the better group size.

    I'd recommend checking velocities and resulting energies.

    If you're shooting squirrel sized game go with the 43.1 grain load.

    If you're shooting at deer/pig sized animals then any of the upper range powder weights should be sufficient.

    Just my guess.

    I plotted group, X and Y against powder and saw nothing that I could understand.

    The only interesting note about the plot was that all lines (group, x and y) intersected at just below 44.1 grains of powder. I'd say that is interesting but most probably meaningless.

    Sorry I couldn't be of more help.

  3. zoeper

    zoeper Well-Known Member

    Feb 20, 2008
    I've plotted the 7 targets as a visual referance, as well as the Average POI of each load. (1 inch grid)
    I agree that a chronograph is required to see if the lighter load have enough velocity. then test around and below that load.
    Thanks for your insights.
  4. steve4102

    steve4102 Well-Known Member

    Mar 13, 2005
    Dan's OCW is a offshoot of the original "Ladder" method. As with the original ladder method Dan's method should be run at 300 yards. 100 yard testing won't tell you much even though he lists 100 as the place to be.