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temperature /speed chart ?

 
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  #1  
Old 08-07-2002, 10:09 PM
 
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temperature /speed chart ?

Does anybody know where I can find a chart that will tell me what the new muzzle velocity will be based on a temperature change?
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  #2  
Old 08-08-2002, 04:48 AM
daveosok
 
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Re: temperature /speed chart ?

I have seen on average with my rifle and handloads a 10 to 12 fps gain per ten degrees. Since this is a variable its impossible to tell you what you may get as a diff but 10 fps is a good all around figure with the rifles I have loaded for and tested.
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  #3  
Old 08-08-2002, 06:01 AM
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Join Date: May 2001
Location: Pennsylvania
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Re: temperature /speed chart ?

Any decent ballistic program will have that feature in it.

Simply run a chart for every ten degrees and keep it in a folder in your backpack or vehical.

The big change will be from 40 or 50 degrees one day and then 80 or 90 the next, which does happen from time to time.

DC
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Old 08-08-2002, 06:37 AM
*WyoWhisper*
 
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Re: temperature /speed chart ?

Unless you live here in Wyo where the temp. swing can be 30 - 40 degrees depending on altitude and time of day.. drives you nuts....

Thats why I am looking for a hand held comp. that can have a ballistics program loaded into it..!!
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Old 08-08-2002, 08:00 AM
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Re: temperature /speed chart ?

Hello Ric

The "Major" changes are the ones to be extra concerned about.
A change of only 10 degrees and 1000 feet elevation is not a major concern. As a matter of fact, a temperature change of 50 degrees really don't change the MOA that much in my 338/416 at 1000 yards. It is 15.5MOA to 15.9MOA at 1000 yards. 4/10ths of a MOA is only 4" at 1000 yards. Not really enough for me to miss the target/animal I am after.

Now if you program a 40 or 50 degree change the "same time" you rise in elevation from 1000 feet to 7000 or 8000 feet, now you have a major change. This is a 17" difference with both temperature changes and alltitude changes combined "in my rifle".

If the temperature and altitude is not "major", the trajectory is not effected "to an extreme".

A hand held computer is available for this if you want to carry it.

I trust my rangefinder, my rifle and my spotter for this change and take a spotter shot 100 or 200 yards away from the animal first, make my correction and then swing back on him for the kill. This procedure is done when the ranges are extreme.
Most times at only 1000 yards I go right for him the first shot.

Later
DC
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  #6  
Old 08-08-2002, 09:51 AM
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Re: temperature /speed chart ?

Darryl,
Doesn't a temp change throw a double whammy on you? Doesn't it first effect the burn rate of most powders therfore the MV that you will have to begin with, then it changes the air density to change drag?
Rick
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  #7  
Old 08-08-2002, 10:20 AM
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Re: temperature /speed chart ?

Hello
At only 1000 yards it seems to matter ONLY when a drastic change is seen in temperature AND altitude.

It dosen't seem to make that big of a difference when in the hunting fields and what I have noticed at the 1000 yard mark. Over 1000 yards and out to 2000 yards it is noticable.

Most people carry their ammo in the pocket of their down clothing in the winter to keep it a bit warmer and keep them in an ice chest, chilled down when it's 90 plus. Is it really needed? Normally the ammo temp is the same as the outside air if you have your ammo in a box and outside with the rifle.
I think if your shooting HOT winter time loads, you better chill them down when you take that SAME ammo into 90 degree heat.

The computer ballistics program is figuring a temperature of the outside air and to an extent the same ammo temperature.

For me, I have not really seen a BIG change within 1000 yards unless the temperature changed by 40 or 50 degrees and also when we combined that with a new altitude location of several 1000 feet.

If your talking about the near same temperature and just a slight elevation change, theres not much change in trajectory. It takes a drastic change in most cases to see a BIG difference.

This has been my experiance.

DC

[ 08-08-2002: Message edited by: Darryl Cassel ]
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