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Thread: Adjusting charge when Adjusting COL

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    Default Adjusting charge when Adjusting COL

    When you guys adjust your COL do you drop your powder charge and work back up? I am playing with a developed load adjusting the overall length to see if I can get a better group. I will be shooting 3 shot groups with the adjustments of -.02, -.01, +.01, and +.02. The load that I shoot is a pretty heavy load. Is the adjustment going to be that great of a change in pressure? I am working with 200gr Barnes LRX in 300 WM with Reloader 25.
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    Hmmm. Back up to what?? What is the load and where is it in regard to maximum pressure. And, where is your COAL in reference to the lands in the throat?

    There is no way to answer your question specifically without knowing these things but in general I don't adjust charge one way and length another. Actually one of the reasons a particular length may be more accurate than another is because it adjusts the pressure and burn efficiency just slightly. If you have a load that is: 1. Less than maximum powder charge. 2. Less than max COAL. Yes you can adjust seating depth without changing powder charge. However, You are listing +/- .020" That could be a very big jump, particularly if you are .010" from rifling contact now. The seating deeper up to .020" will make some difference in pressure but I cannot say how much.

    Your component choices are good and they should shoot well in a good barrel. I have found the CCI-250 rifle primer a good choice for primer in the 300 WM.
    Last edited by Murphy; 03-15-2012 at 16:25.
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    I am currently .05 off the lands and Quick Load says that i am 700 psi below max pressure. I don't know how much I trust their max pressure because I shoot loads out of other guns that the program says are " dangerous loads" but have now pressure signs when shooting. I use the CCI 250 primers also.
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    Then I'd say you can move +/- .020" without worry. Load a few and watch for pressure signs.
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    My limited experience with Barnes loads (about 4 different rifles and a dozen loads) was that seating closer than 0.050 to the lands can sometimes result in sharp increases in pressure. Loading deeper however, has often resulted in slightly lowered pressure, despite the bullet taking up additional case volume.

    My experience is minimal, but that's what I've found. If I hit pressure signs before I think I should with a Barnes load, I usually try seating deeper before I reduce the charge. I am currently using Ramshot data in a 30-06 with 168 gr TTSX. It's a full 3 gr over what Barnes recommends, but at 0.070 off the lands, it's no problem in my gun and right in the accuracy sweet spot.

    Still, as Murphy says, +/- 0.020 isn't huge change if you are already that far back. I'd wouldn't adjust charges until I tried it.

    Yk

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    I test COL first then adjust the charge. It has worked well for me. I have a mid load, at SAMMI COL then move up. With Barnes I will typically try .1, .07, .05 off the lands in that order. .07 off the lands has worked with most all my loads if I have magazine room. One of those three will shoot much better and then I tinker with powders using the COL that shot the best group. It has saved a bunch of load workup time. Usually a couple of times out to the range and I have a load worked up to the magic 1 moa or better. If you are an accuracy nut, you can REALLY play with the variables once you are in the ball park.

    I am playing with the 200 LRX in my RUM (they were originally sold as 200 TTSX), and have some loaded up ready to go in the above fashion. They sure are LONG suckers. I am anxious to see how they do in the Winnie. Let us know.

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    Quote Originally Posted by Daved View Post
    I test COL first then adjust the charge. It has worked well for me. I have a mid load, at SAMMI COL then move up. With Barnes I will typically try .1, .07, .05 off the lands in that order. .07 off the lands has worked with most all my loads if I have magazine room. One of those three will shoot much better and then I tinker with powders using the COL that shot the best group. It has saved a bunch of load workup time. Usually a couple of times out to the range and I have a load worked up to the magic 1 moa or better.
    That's exactly the method I landed on for my last couple of load tinkering sessions. Worked for me also.

    Yk

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