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Thread: re-zero for winter?

  1. #11
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    Quote Originally Posted by markm View Post
    Granted there are some powders that are pretty temp sensative, there's a lot of info that contradicts this. I mean.. I've seen the Davidson brothers put one round in the sun and one round in an ice chest and shoot them same POI.

    Barrel temp is the biggest factor. I was reading an article (I forget where now - I think accurateshooter..?) about barrel temp regulation. And the gist of it was... if you're not regulating your barrel temp, precision powder measurements don't matter.
    We have the freezer outside the door every winter. What happens is people zero in the summer temps and shoot low & miss in the winter when the grouse season is. Another issue which is not taken in to consideration with the mentioned ice-box example is the fact that cold air is denser than warm air: there is more air resistance in the cold.

    Barrel temperature may affect POI especially on non-freefloated guns, but the real issue is the powder temperature. If I shoot at relatively rapid pace the round in the chamber has no time to warm up to cause shift. But if I shoot the barrel hot and leave the round in the chamber for few minutes, sure it'll have different POI.

  2. #12
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    Depends on the powder. W748 will blow primers if you develop a hot load in the winter.

    And no question that air density changes... but that's factored into your ballistics app.
    "You people have too much time on your hands." - scottryan

  3. #13
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    I'm with markm on the barrel type side of this discussion.

    In fact, I have a battery operated boot sock that keeps my barrel warm when I'm sitting in a tree stand here in Wisconsin.

    I know, I know,,, seems silly but, the results speak for themselves. My summer and winter zeros are identical....

    As long as I don't run out of batteries

  4. #14
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    Wouldn't it just be easier to head to the range on a cold day and figure a new zero? Hell, the difference between 60F and 0F on my 30-06 loads is only 3" at 200 in a vertical line. We are only talking 6 clicks to bring it in based on temp.

  5. #15
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    Quote Originally Posted by AKDoug View Post
    Wouldn't it just be easier to head to the range on a cold day and figure a new zero?
    That is what I am suggesting people should do.

  6. #16
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    Quote Originally Posted by AKDoug View Post
    Wouldn't it just be easier to head to the range on a cold day and figure a new zero? Hell, the difference between 60F and 0F on my 30-06 loads is only 3" at 200 in a vertical line. We are only talking 6 clicks to bring it in based on temp.
    This is the kind of stuff I was hoping to hear. I would really like to avoid keeping track of 2 different zeroes. For reference the weapon i started this thread over is 14.5 bcm middy with 2 Moa aimpoint shooting a 64gr nosler bsb.

  7. #17
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    My other post was referencing The_Hammer_Man's post. I assumed he was talking about scoped hunting rifles.

    With a 2 moa red dot you are not going to see enough difference to even have to dick with it.

  8. #18
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    Quote Originally Posted by AKDoug View Post
    My other post was referencing The_Hammer_Man's post. I assumed he was talking about scoped hunting rifles.

    With a 2 moa red dot you are not going to see enough difference to even have to dick with it.
    Simply awesome. Thank you. I think I will confirm or re- zero on the most temperate day I can find. Something like 55 degrees with mild humidity. That way the differences are smaller no matter if it's 100 or 0 degrees outside. If I'd know then what I know now..... I wouldn't have chosen a hot humid summer day to set the base line for poa/poi.

    Until then...... I am sure it will be fine. Not a lot of ranges past 100 yards where I live. I think I am going to search for a place to get out to 200 and 300 yards. It would interesting to see just if a "summer" zero actually effected by any measurable amount in the dead of winter with a rds on top of a 14.5".

    Thank you to every one who responded in this thread. Very helpful.
    Last edited by kenndapp; 11-20-12 at 17:43.

  9. #19
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    Yes, I was referring to my "bambi bumper" which is an 18" barreled Grendel.

    With a red dot I would be hard pressed to discern the difference in impact points due to the size of the dot with most of them.

    The barrel warmer thing started with my grandad and his muzzle loader that he hunted deer with. Warm barrel shots were much faster/better than with a cold one. Especially with blackpowder. I'm sure with most commercial ammos this really isn't a major concern.

    It's sort of a family tradition and it works... so why fix it?

  10. #20
    Dano5326 Guest
    Temp variation, inside of 600m, is a feature of the powder used, not how the bullet "flys" Modern military loadings tempature stabilized powder show no appreciable difference.

    Sniper schools used to teach 1moa per 20degrees. I have not found that to be accurate.

    I have no idea on the variance of commercial loads.

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