how does rain affect bullet flight?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by AtownBcat, Sep 8, 2010.

  1. AtownBcat

    AtownBcat Well-Known Member

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    I wanted to go out and test today but it was raining and I was not sure if the results would be accurate.
     
  2. justgoto

    justgoto Well-Known Member

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  3. SBruce

    SBruce Well-Known Member

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    Can't say about the bullets actual flight, but I know from experience that moisture inside a barrel can throw a shot off!
     
  4. Kevin Thomas

    Kevin Thomas Well-Known Member

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    AB,

    One of the primary differences that you're likely to notice is that your trajectory will be flatter, compared to your zeros from a nice, sunny day. This isn't due to the rain itself, per se, but to the lower barometric pressure that accompanies (or allows) the rain. I've seen changes of a minute or better between two silhouette matches, the first fired in a nice clear morning, the second later that afternoon as a front moved in and it began raining (gotta love Missouri). I had to come down a full minute to a minute and a half for the second (afternoon) match. Same gun, same ammo, rain (and barometric pressure) being the only difference.

    As SBruce pointed out, water in the bore or chamber can be a real problem, but that's actually another issue. I'll add flash suppresors to the mix here, even if the water doesn't make it inside the bore. Those that don't provide adequate clearance, like a standard (not NM reamed) M1A/M14 suppresor, will give wild shots with the first shot, every time.

    Kevin Thomas
    Lapua USA
     
  5. AtownBcat

    AtownBcat Well-Known Member

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    Ok, But how does a bullet impacting a drop of rain not make the POI move all over the place??
     
  6. trebark

    trebark Well-Known Member

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    I agree that it doesn't make sense that impacting rain drops on the way to the target should deflect the bullet, but it does not. I actually like to shoot in the rain as it is the ultimate wind flag. You can judge the wind at every distance from rifle to target. The best three shot group I ever shot was in an f-class match in the pouring down rain at 800 yards. I put the first shot in the 10-ring, target came back up with the 2" white spotter in the hole. Next shot, the range mastered report "you hit the spotter". Next shot, range master reported "you hit the spotter!". I just shot a 2" group at 800 yards in the pouring down rain! One of the huge contributing factors was the fact that I could just the wind perfectly.
     
  7. AtownBcat

    AtownBcat Well-Known Member

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    Is it possible that the air flow around the bullet keeps the rain from actually making contact?