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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
I’m always busy at the wrong time…for SCIENCE!!!😡🤣. Anyone ever shoot at these temps and get chrono numbers?
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<blockquote data-quote="Calvin45" data-source="post: 2713205" data-attributes="member: 109862"><p>Very true…the closer you are to the ragged edge the more likely it is that change of any kind from the original conditions of the load development will be trouble. </p><p></p><p>I posted not long ago about reverse temp sensitivity with lively discussion to follow, learned a bunch. With a few powders now (8133 and superformance in particular) I've observed that loads I worked up in June were up to 120 fps faster and causing sticky bolts in January. And I'm not alone it turns out. </p><p></p><p>The fruit of that discussion was a few conclusions </p><p></p><p>#1 reason has to be the "pixie dust" they put</p><p>In temp insensitive powders (or else you WOULD observe this effect with othwr powders too…I do not…rl22 runs about as much slower in January haha) </p><p></p><p>It has nothing to do with contraction/shrinking the barrel due to cold - UNLESS you've loaded a warm cartridge from your pocket into a frozen rifle haha, a very possible scenario when hunting - but if the bullet and the barrel are both cold it won't cause pressure from a tighter squeeze…in fact a helpful gent on that thread cited data that shows that both copper and lead have higher thermal expansion ratios than steel…to whatever degree the barrel MIGHT shrink, the bullet will MORE. </p><p></p><p>#2 consideration, though again I don't observe this with most powders so it's not a major factor, was hypothesized by the very knowledgeable Kirby Allen, is that it's not that the barrel constricts, but is more "reluctant" to bend and flex in the extreme cold (as am I <img class="smilie smilie--emoji" loading="lazy" alt="🤣" title="Rolling on the floor laughing :rofl:" src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f923.png" data-shortname=":rofl:" />). All materials with any elastic properties lose elasticity with decreasing temperature. We all know about barrel harmonics and how the steel does in fact move during the bullet's transit…in -20 to -50 it really doesn't feel like moving. I can't prove that his theory is correct but it makes very good sense to me</p></blockquote><p></p>
[QUOTE="Calvin45, post: 2713205, member: 109862"] Very true…the closer you are to the ragged edge the more likely it is that change of any kind from the original conditions of the load development will be trouble. I posted not long ago about reverse temp sensitivity with lively discussion to follow, learned a bunch. With a few powders now (8133 and superformance in particular) I’ve observed that loads I worked up in June were up to 120 fps faster and causing sticky bolts in January. And I’m not alone it turns out. The fruit of that discussion was a few conclusions #1 reason has to be the “pixie dust” they put In temp insensitive powders (or else you WOULD observe this effect with othwr powders too…I do not…rl22 runs about as much slower in January haha) It has nothing to do with contraction/shrinking the barrel due to cold - UNLESS you’ve loaded a warm cartridge from your pocket into a frozen rifle haha, a very possible scenario when hunting - but if the bullet and the barrel are both cold it won’t cause pressure from a tighter squeeze…in fact a helpful gent on that thread cited data that shows that both copper and lead have higher thermal expansion ratios than steel…to whatever degree the barrel MIGHT shrink, the bullet will MORE. #2 consideration, though again I don’t observe this with most powders so it’s not a major factor, was hypothesized by the very knowledgeable Kirby Allen, is that it’s not that the barrel constricts, but is more “reluctant” to bend and flex in the extreme cold (as am I 🤣). All materials with any elastic properties lose elasticity with decreasing temperature. We all know about barrel harmonics and how the steel does in fact move during the bullet’s transit…in -20 to -50 it really doesn’t feel like moving. I can’t prove that his theory is correct but it makes very good sense to me [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
I’m always busy at the wrong time…for SCIENCE!!!😡🤣. Anyone ever shoot at these temps and get chrono numbers?
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