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HP-38 Temperature Sensitivity?


zhunter

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I am developing a load for HP-38 and I'd like to know if it has any temperature fluctuations? My go to has been N320, but looking for a substitute and HP-38 looks good as long as there are no surprises from changing temps.

Anyone have any info or data?

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I have been using HP38 / Win231 for several years. I know of NO temperature sensitivity.

BUT there have been letters published (reportedly from Hogdon) that HP-38 / Win231 is being dropped from production in the next few years. I have seen the letters, but I have no idea how accurate / reliable these stories are. I continue to use this powder. Best wishes.

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been using in Florida for 27 years no problems with the temp. From 2009 hp-38 and 231 have been the same powder. We have a reloading company 25 years ago used hp-38; you would take your milk jug over and he would fill it up for a low cost.

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been using in Florida for 27 years no problems with the temp. From 2009 hp-38 and 231 have been the same powder. We have a reloading company 25 years ago used hp-38; you would take your milk jug over and he would fill it up for a low cost.

Good to know, I'm in Florida too, but my worry is going to Nationals and getting chrono'ed on a cold morning (unlikely in August), but I never like leaving anything to chance.

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I have seen temperature-caused FPS swings using W231/HP-38 in .45acp (not much since 45 is so slow anyway) but it's there. The powder really doesn't like the cold. Rarely an issue in Florida but the FPS difference between 90 degrees and 50 degrees is significant. And the colder it gets, the slower it goes. If temp swings may be an issue but you love W231, I suggest using WST. Very similar to W231/HP-38 but much less temp sensitive.

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It depends on how close to the power factor floor you like to run. If you're loading 126 for a 125 PF then I could see a reason for concern. I load 136 for minor and 172 for major. I never get close to failing chrono at any temperature or altitude.

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