At what temp does powder stability become an issue


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Redneck with a 40
April 23, 2009, 10:59 PM
Is it above 70 degrees and below 30? Whats the high and low point where it severely affects the powder? I know Varget is more stable than most powders, but what's the real impact on ordinary powders?

The max temperature I'll ever be shooting in is about 85 degrees in the summer and about 30 degrees in the winter.

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Zak Smith
April 23, 2009, 11:14 PM
It depends on the powder and the load.

I have a .260 load I chronod at about 5F and 100F, it was within 10 fps.

That is probably nontypical-- exceptional.

The Hodgdon "Extreme" powders have a reputation for being less sensitive. I have shot my long-range loads in .260, .308, and .338LM in a variety of temps with no change in long-range POI.

ranger335v
April 24, 2009, 12:13 AM
I've never heard anything about that as a specific factor for any powder but doubt you will see much difference within the temp ranges you state. I do know that the differences vary with the powder, it's not something anyone could qualify in a table.

Any change in powder burn rate is likely to be directly variable with temp, not a stepped range.

Shoney
April 24, 2009, 03:33 AM
I've done a lot of shooting at 35-45 below. A few times on special elk hunts, quite a few times on deer hunts, and a lot of hours for varmints. With the larger capacity cartridges, the reduced performance was not noted, but for 6mm Rem and 222 it was very noticeable.

Over the years I particularly remember a number of large whitetail and mule deer bucks, and several does where normally I would have expected the 6mm should pass through completely. They did not. The blood shock area around the entrance wounds was considerably less as well; much less than those taken at 10 below and up.

I surmised that there is a combination of factors for cold weather, powder being only one. Cold shrinks metals and they do strange things such as becoming more brittle. I always have wondered how much the bore deminishes as compared to the copper lead bullet. Either scenario - - 1.) bullet shrinks less and "sticks" in bore, or 2.) bullet shrinks more allowing gas to escape past; - - will result in decreased performance. Also reduced brisance of the primer and reduce capability of the power could add. Another possibility is that the brass may be shrinking and expansion of the case during firing may also contribute to the diminished performance.

A lot more people can document pressure spikes at higher temps.

Silverado6x6
April 24, 2009, 10:22 AM
I live in Alaska and have reloaded purpose type of extreme cold loads starting with magnum primers, especially my .308 gas gun rounds and any of my handgun rounds using Bluedot which is cold weather sensitive. Instead I try to use Unique. The .308 I use H4895 instead of IMR4895 because the former is more cold tolerant and a hair bit faster burn rate wise.

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