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? Temperature Sensitive ?

 
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  #1  
Old 12-10-2007, 10:41 PM
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? Temperature Sensitive ?

Certain powders are temperature sensitive - ok. What are the effects of this property? What are some of the more temperature sensitive powders? What are some of the less temperature sensitive? Is there a cure for this disease?

I have discovered that there is much more to shooting and doing it at more than "normal" ranges than I ever realized. And I got my first gun the year that Ike was elected President the first time!

Oh well, some of us are just slow learners.
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  #2  
Old 12-10-2007, 11:03 PM
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Actually, all powders are temperature sensitive to some extent. A general rule of thumb is that ball powders are more sensitive than extruded powders.

Some of the effects of cold temperatures that you will notice are lower velocities, slow or hang fires etc. High temperatures will cause just the opposite and can lead to excessively high pressures, blown primers etc.

This is why its important to write down the temperature when you are testing a load. I always let my rifle and ammo adjust to the outside air temperature before I shoot at the range, so I can record accurate results for the conditions.

If you have a load that shoots good at say 70F and you notice it starts mis-behaving at 30F, a couple things can be done if you have to shoot at 30F or colder. I've put a hand warmer (the little disposable ones) in with my ammo and wrapped it in a jacket. If you are hunting, you can carry a couple shells in a pocket to keep it warmer, then load it just before you shoot.

On the flip side, too hot of temperatures can raise pressures significantly. Although I've never done it, I've seen guys keep loads in a cooler in the summertime, because if that ammo got hot, it would be too high pressure.

Hope some of that helps, I'm sure others will add a lot more detail.

AJ
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Old 12-10-2007, 11:54 PM
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Temp sensitive powder

The worst temp sensitive powder was called cordite (long sticks of
powder that was loaded by the number of sticks required to reach
a given velocity)

There are a lot of powders in all brands that are temp sensitive but
the least sensitive I have found has been Hodgdon Extreme line of
powders.

I allways try to work up loads with these powders first to avoid this
problem ,But sometimes I'm forced to use something else in order
to get an accurate load.

One of my best loads for the 7/08 uses H414 but from 50o to 100o
velocity increases 130 ft/sec (H414 is ball powder).

And Reloader 19,22 and 25 are very sensitive also.

I hope this helps
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Old 12-11-2007, 12:10 AM
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Hodgdon has a line of extreme powders that have very little temp sensitivity.

10-15 fps variation between 30-100 deg. if I remember right, go check out their page; extreme powder line.

varget, H-1000, retumbo... just to name a few
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Old 12-11-2007, 07:08 AM
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Quote:
On the flip side, too hot of temperatures can raise pressures significantly. Although I've never done it, I've seen guys keep loads in a cooler in the summertime, because if that ammo got hot, it would be too high pressure.
Not only do I do that, but I try not to let a round sit in the chamber much more than 15 seconds before I shoot. The internal chamber temperature can be significant even if your barrel is not "hot". Heat transfer begins immediately because brass is a good thermal conductor.

These techniques are how I test cold weather loads in the summer.

If you work at maximum pressures then you must consider that all powders are temperature sensitive.
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  #6  
Old 12-11-2007, 07:37 PM
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Thanks to all! This is about what I expected and is reason enough to draw some logical conclusions:
1. Temperatures where I live fluctuate from about 15F to 110F. A large enough range to cause problems with some powders. Some of these problems can be dangerous.
2. I like ball powders because I like ball powders (has something to do with when I didn't weigh every single one).
3. Ball powders are as sensitive as they come.

Conclusion:
I need to shoot lots more so that I will be able to establish a reasonable sd for each temperature.

I'll share this with Mrs. North in the morning before she wakes up good. Its really a safety issue u c. That's the ticket and this is after consulting with people that have lots of experience. Yeah!

Seriously thanks guys.
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  #7  
Old 12-11-2007, 07:51 PM
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Unvisable, I also use the hodgdon extreme powders and have no problems.

The high pressures become a problem when using max pressure loads. I do not shoot a lot in hot weather so it is not a problem for me, but I imiagine you do so load accordingly.

You might want to take a look at ramshot powders if you like ball powders. I don't really use them, but they claim to be less temp sensitive. I can't say for certain.
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