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Posted: 6/28/2009 3:42:58 AM EDT
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It's not. But don't expect loads developed at 65 or 70 degrees to produce the same pressure at 90 or 100. A load on the ragged edge at low temp may push over the edge when temps reach 95 to 100F. That applies to all gunpowders.
It's a good idea to watch lot to lot variation of Alliant rifle powders in my experience. |
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I shoot/hunt in the deep south where a huge temperature swing summer to winter is the norm. Hodgdons had some extreme velocity spread data on their website a few years back, but removed it once it became dated. It was based on a 308 Winchester firing a 168gr Sierra Match King at 0 & 125 degrees F. At the time, my printer was fried from a lightning strike that blew right thru the surge protector so the below data was simply hand-copied. I have emailed Hodgdons asking for their complete data, which contained about 30 different powders IIRC, but have never received a response. Here is what I have:
POWDER TYPE/0-125* F EXTREME VELOCITY SPREAD (FPS) 1. H4350/4 2. Varget/8 3. H4831C/10 4. RL12/26 5. AA4350/29 6. AA2460/36 7. IMR4064/46 8. VV N550/49 9. RL15/50 10. VV N140/50 11. AA2520/63 12. IMR4350/ 67 13. RL22/75 14. RL19/94 15. AA3100/113 16. W748/114 17. VV N560/121 18. IMR4831/127 19. IMR4895/166 |
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It's low on the totem pole compared to most others.
I shoot the same load year around with RE15, an over max load and have no problems with temps. Was out Wed at the range in the middle of the day, temp was 108 in the shade and didn't show pressures. Comparing the shape of the primers from winter to summer, very little, if any difference. I've had more pressure problems from Varget. 'Borg |
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