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Measuring Powder Temperature

 
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Old 12-10-2013, 03:34 AM
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Measuring Powder Temperature

Require some scientific guidance on peoples understanding of the concept of powder temperature (PT).

1. Definition of PT and how this effects internal ballistics;
2. Methods used to determine PT;
3. Ability to accurately determine PT amongst ammunition natures to include variations in powder and cartridges;
4. Correlating ambient temperature to support an accurate determination of PT for inputs in ballistics software.

I've no doubt this has been covered somewhere in the past threads so feel free to point me in that direction. It is however a dry topic and thus I've found information hard to come by.

I currently use Applied Ballistics software which enables PT as an input but have experienced significant inaccuracies when doing so, which may simply be attributed to my understanding of PT.

Input appreciated. Cheers Willo.
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Old 12-10-2013, 10:24 AM
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Location: Texas
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Re: Measuring Powder Temperature

Quote:
Originally Posted by willo View Post
Require some scientific guidance on peoples understanding of the concept of powder temperature (PT).

1. Definition of PT and how this effects internal ballistics;
2. Methods used to determine PT;
3. Ability to accurately determine PT amongst ammunition natures to include variations in powder and cartridges;
4. Correlating ambient temperature to support an accurate determination of PT for inputs in ballistics software.

I've no doubt this has been covered somewhere in the past threads so feel free to point me in that direction. It is however a dry topic and thus I've found information hard to come by.

I currently use Applied Ballistics software which enables PT as an input but have experienced significant inaccuracies when doing so, which may simply be attributed to my understanding of PT.

Input appreciated. Cheers Willo.

WOW !!!

That's a tall order and smarter people than me will have to chime in on this one.

I use 70o as ambient and test different loads to see the change if heated to 100o or cooled to 30o
(The normal range of temperatures I hunt in)

Each powder has a difference tolerance for temperatures so when I can get the accuracy and velocity that I want I use the extreme powders from Hodgdon because they are very stable in this range.

I am forced to use other powders at times because they produce better results and have to adjust to these temperature changes and the effects on POI.

I doubt that there is any common number that you could use to calculate the effects of temperature on different powders, But maybe some of the guys can help you.

Interesting question, Hopefully I can learn something from this.

J E CUSTOM
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Old 12-10-2013, 12:56 PM
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Location: Meridian, Idaho
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Re: Measuring Powder Temperature

I can't even imagine the responses this going to get and the amount head spinning jargon. I did look at the hodgon site yesterday and they have a comparison of velocity change over 125degree temp range for several powders.

http://hodgdon.com/smokeless/extreme/page2.php#top
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Old 12-10-2013, 02:12 PM
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Join Date: Jul 2004
Location: Texas
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Re: Measuring Powder Temperature

Quote:
Originally Posted by BrentM View Post
I can't even imagine the responses this going to get and the amount head spinning jargon. I did look at the Hodgdon site yesterday and they have a comparison of velocity change over 125degree temp range for several powders.

http://hodgdon.com/smokeless/extreme/page2.php#top

That is a good reference to use, and may give the poster what he needs for a particular
powder.

I don't know how accurate the charts are, but my loading records pretty much follow the same
Percentages. when I use the 30 to 100o range.

I really like the extreme powders but sometimes I have to use the others and deal with there heat sensitivity.

J E CUSTOM
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Old 12-10-2013, 02:46 PM
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Location: Meridian, Idaho
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Re: Measuring Powder Temperature

Especially with the lack of availability today. I am using IMR 4064 in my 204 right now. The site says it is not super sensitive but who knows unless you test it. They used a 308 in their test. That is about twice the amount of powder I am shooting. Next time out I think I will stick a few in underwear and few next to the heater vent and test them compared to outside temp. I zeroed and shot at 10F Sunday, which is what I expect our wolf hunts to be close to all winter. Brrrrr freaking brrrrrr.
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  #6  
Old 12-10-2013, 09:15 PM
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Join Date: Dec 2013
Posts: 5
Re: Measuring Powder Temperature

For those using powder temperature as an input in any particular ballistic calculations, can you explain how you determine your temperature input? The reason I ask is unless there is a measured correlation of thermal conductance between brass (or cartridge) and powder any temperature input is invalid and results in vastly variable inputs.

A lot of people will tell you to put ammunition on 'ice' and as a subsequent action record a 0 degree celsius input for temperature when zeroing for instance. The problem is both brass and particularly annealed brass and powder have unique heat transfer properties which would need to incorporate conductance formulas from ice to brass to powder for instance.

As a simply test using a RUAG .338 SWISS P cartridge in the freezer overnight and with the use of a calibrated laser thermometer, removing the powder from the cartridge the following morning only recorded 16 degrees celsius. Powder on its own in the freezer recorded 1-2 degree celsiuis.

Have others experienced something similar?
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