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Thread: New ammo batch - 3 MOA shift left

  1. #1
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    New ammo batch - 3 MOA shift left

    Is this common?

    I switched to a new batch of ammo (powder and bullets) and I was 3 MOA left. The wind was crazy (16mph) changing directions every few minutes and I dropped about 15 rounds and 2 stages before I figured out what happened. I’ve never had this happen before. Why the big shift?
    Why do the loudest do the least?

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    Not in my experience. Assuming handloads?


    At what distance was the 3 MOA shift from prior load observed? Extreme range, 600 yds and out or from a couple hundred and out? And was the 3 MOA differential elevation, windage or both?
    And we are talking different lots of the same bullets and powder?
    Depending on specific powder, I’ve had some fairly extreme differences in pressures/velocities, not as severe with bullets of same type/manufacturer.
    I have blended 8 pound kegs of different lots together to avoid this.

    I would’ve “proven” the new batch prior to a significant match.
    Last edited by gaijin; 05-04-19 at 17:28.

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    It was actually 4 MOA left and 0.5 MOA low. I have never seen this before and I’ve used this load for years. I noticed it at a stage with 323 yards and 416 yards. Before the next stage I ran over to 100y and confirmed it since the wind was stupid.

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    What caliber Euro?

    A .224 pill, even heavy, drifts like a bitch in wind.
    You have 15/20 mph wind drift plugged in ballistic program and it exceeded that?

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    It was definitely not wind because I moved over to a different range and shot at 100y with high berms. Maybe 5mph of wind made it down there.

    .223. I chrono’d the old load yesterday at 2746 77gr TMK. I didn’t chronicle this load though yet

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    Not assuming it as a given, but is it the same weapon?

    Elevation could obviously be a charge/velocity issue, the windage (since you confirmed it wasn't the gusts that were affecting it) is something else.

    Optic or mount? Some kind of barrel, muzzle, or muzzle device defect causing a deflection to the left? At those ranges the "spin drift" shouldn't be an issue, and if it was it would be to the right due to the RH twist (correct?).
    Last edited by ABNAK; 05-04-19 at 19:15.
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    Interested to hear how the new batch chronos.

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    I have witnessed different powders/bullets cause quite a shift. Usually it’s not as drastic as 4 MOA but it isn’t out of the question.


    What was the old load? What was the new load?


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    I have seen .5gr shifts in weight with my powder thrower when going from one powder lot to another. I was using TAC when that happened, and TAC has long worked well for me as an accurate plinking load.

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    Quote Originally Posted by lsllc View Post
    I have witnessed different powders/bullets cause quite a shift. Usually it’s not as drastic as 4 MOA but it isn’t out of the question.


    What was the old load? What was the new load?
    Serious question (I'm not a reloader): What about a powder change would make a bullet skew left or right? Sure, a minute amount but 3-4 MOA? I can easily digest the up or down variance as it relates to velocity (hotter batch vs. not as hot). Wouldn't there have to be a sizeable outlier (like burr in the barrel, slightly-off muzzle device that "bumps" the bullet, loose or re-mounted optics) in the equation for windage discrepancies like that?
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