Accuracy in constant heat

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Re: Accuracy in constant heat

Post by Apollo » 04 Aug 2014, 5:30 pm

There are so many factors involved.

Factory ammo or reloads that's using temperature sensitive powder. The temperature when you sighted in and/or worked up a load. The difference in the atmosphere and heat / cold currents of air.

If you reload then using temperature insensitive powders like ADI's should even out the playing field but 45c is getting a tad warm.

I've often shot / tested early hours of the morning when it's about a few degrees then warm afternoon around 30c and notices very little difference.

The biggest affect I've found is shooting targets at 500 metres across deep gullies and noticed the POI change quite a lot due to the air currents moving down the gully from hot to cooler ground. So your accuracy change might have numerous reasons for happening depending on distance as well.
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Re: Accuracy in constant heat

Post by Warrigul » 04 Aug 2014, 9:35 pm

Apollo wrote:There are so many factors involved.

Factory ammo or reloads that's using temperature sensitive powder. The temperature when you sighted in and/or worked up a load. The difference in the atmosphere and heat / cold currents of air.

If you reload then using temperature insensitive powders like ADI's should even out the playing field but 45c is getting a tad warm.

I've often shot / tested early hours of the morning when it's about a few degrees then warm afternoon around 30c and notices very little difference.

The biggest affect I've found is shooting targets at 500 metres across deep gullies and noticed the POI change quite a lot due to the air currents moving down the gully from hot to cooler ground. So your accuracy change might have numerous reasons for happening depending on distance as well.


Even ADI powders, even though they are better than most, vary with temperature and serious long range competitors take steps to minimise variation due to heat differential. I keep mine in the shade at all times even if it is just a hat thrown over the bullet bar. AR2206 was known to dislike high temps and this why AR2206H was introduced.

In a close to the edge load excess heat can be enough to cause issues.

The single most telling factor on accuracy when shooting in strong heat is being able to use a decent magnification. In mirage often it is neccesary to back off heavily, one day at 1000 I had to swap out my 36x weaver and fit the old variable as anything over 24x was unuseable.

Mirage is very useful in calculating windage if you know how to use it.
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Re: Accuracy in constant heat

Post by Westy » 05 Aug 2014, 7:49 am

Warrigul wrote:The single most telling factor on accuracy when shooting in strong heat is being able to use a decent magnification. In mirage often it is neccesary to back off heavily, one day at 1000 I had to swap out my 36x weaver and fit the old variable as anything over 24x was unuseable.


I was going to say the same thing except the mirage also gives your a false reading on the target IMHO. the bigger the magnification the bigger the miss!!!
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Re: Accuracy in constant heat

Post by steyroy » 05 Aug 2014, 4:04 pm

Warrigul wrote:Mirage is very useful in calculating windage if you know how to use it.


I'm obviously doing it wrong because it just makes me shoot wobbly :lol:
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Re: Accuracy in constant heat

Post by Farmjer » 06 Aug 2014, 3:10 pm

Chulley,

Check out Aussie Outback ammo if you want something consistent regardless of temperature. That's exactly what it's designed for.

Check this out - Aussie Outback Ammo groups in different temperatures
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Re: Accuracy in constant heat

Post by artimu » 20 Aug 2014, 3:00 pm

Have a read of this Chulley.

Environmental factors that affect accuracy
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