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Powder Temperature Sensitivity

 
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  #8  
Old 01-27-2009, 09:28 PM
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Join Date: Feb 2008
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Re: Powder Temperature Sensitivity

Unfortunately, as stated above, the info you require just isn't out there.

I can tell you for certain that Alliant powders are the worst for increasing/decreasing in power released with changes of temperature, and the best for not showing swings in power released are Hodgdon Extreme powders, most ball powders are stable until extreme cold/hot situations show themselves.

One thing is for sure, if you work up loads in cooler months with Alliant powders, you will most likely run into trouble in the warmer months, I have had blown primers with a load worked up in winter, and then used in spring, a temp change of only 10 degrees C, go sky high in pressure causing me to abandon shooting for that day until I adjusted the powder charge.

The only way to know what a powder will do in fluctating temps is to test it at varying temps.

Cheers.
MagnumManiac.
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  #9  
Old 01-27-2009, 10:04 PM
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Re: Powder Temperature Sensitivity

Quote:
Originally Posted by MagnumManiac View Post
I can tell you for certain that Alliant powders are the worst for increasing/decreasing in power released with changes of temperature, Cheers.
MagnumManiac.

Tell that to my 300 RUM. I have tested her with RL-25 with 20 FPS difference from 75ish to -2 degrees F.

Alliant isnt as sensitive as you may be led to believe. I have seen similar results with my 308 in RL-15 and anotehr 300 RUM barrel I used to use. Granted going from 75 to 110 may be a different story. For me and most other hunters, I wont be hunting in 110 degree air and If I had to, I dont push my loads to the max anyway so it would make little difference in the excessive pressure department. For most hunters, they develop their loads in fairly warm air and hunt in much cooler air.

On the flip side of the coin, I know others who have experianced 100+ FPS in a 80 degree swing with RL powders. It just isnt predictable. Does this meen that Alliant is the MOST sensitive? Hardley. This is why one should develop a load their rifle likes best and go from there. Rifles are not biased about ambient temperatures like we are. They are harmonicaly biased though. This should come first in a load selection. You can always learn how much difference there is in an 80 degree spread and adjust you palm program accordingly. Harmonics come first. If you end up with a minimal affected load, then that is a bonus.
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Quote:
Originally Posted by Broz View Post
Please just answer one very simple question. Why would anyone shooting long range load a low BC , low SD 168 gr offering in a 300 win???????

My answer to this is. The only reason is to make the 7 RM look good. There is no other reason.

Jeff.

Last edited by Michael Eichele; 01-27-2009 at 10:10 PM.
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  #10  
Old 01-27-2009, 10:56 PM
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Join Date: Jan 2009
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Re: Powder Temperature Sensitivity

Quote:
Originally Posted by meichele View Post
It would be hard to develop a chart since so many variables go into the sensitivity of ANY powder. Things like case capacity, load density, bullet weight and cunstruction over the charge, twist rate in relation to the bullet used, free bore, and of course what spread of temperature youre shooting in.

You will use some powders that are not famous for insensitivity and you might find that in your circumstances the difference with 80 degrees of swing is minimal when another shooter with other circumstances finds a HUGE increase or decrease in velocity. You cannot accuratly predict temperature sensitivity and IMHO too many shooters place too much importance on this. Find a good load, learn how much it increaces and decreaces in a given temp spread and BE HAPPY! None of us should be pushing a load to the max where a few degrees sends the load over the line.

Just my .02 cents
I believe the thought was that a chart or relative performance index (RPI) or powder temperature sensitivety would be a useful tool. Certainly, each instance of a bullet-rifle-load combination is going to produce different results, but a RPI allows you to gain an idea of performance and can assist in selecting a power before you spend much time investigating it. Similar to the use of a burn rate chart. RPI charts are quite common in the aircraft and auto industies.

Having said all that, as you mentioned, I intend to characterize the temperature versus velocity of my 300 wsm load (using reloader 19) so that I can better hit the target and game. I'll post the data as I gather it.
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  #11  
Old 01-28-2009, 09:47 AM
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Re: Powder Temperature Sensitivity

I'm sure it depends on loads, but I've found IMR to be less sensitive than Hodgdons pretty much across the board. Personally, I think Hodgdon's marketing is a bunch-o-hooey without real basis.
That said, I use them, and I'm glad for their offerings.
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  #12  
Old 01-28-2009, 04:48 PM
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Re: Powder Temperature Sensitivity

Quote:
Quote:
Originally Posted by Slim_T View Post
Having said all that, as you mentioned, I intend to characterize the temperature versus velocity of my 300 wsm load (using reloader 19) so that I can better hit the target and game. I'll post the data as I gather it.
You might also try RL17. I believe they are advertizng it as stable at extreme temps.
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  #13  
Old 01-30-2009, 11:52 AM
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Re: Powder Temperature Sensitivity

Vintec,

This is the info that Hodgdon was putting out after the Extreme line came out.




Hope you can read it....JohnnyK.
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  #14  
Old 01-30-2009, 01:08 PM
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Posts: 148
Re: Powder Temperature Sensitivity

Johnny,

Is there a link to this info or is this a scanned image.

Thanks

Vince
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