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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Barrel fluting post build affect accuracy?
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<blockquote data-quote="Brent" data-source="post: 70037" data-attributes="member: 99"><p>LB,</p><p></p><p>How do you explain a press fit/interferance fit between two cylindrical parts? The part being inserted into a bore is a couple thou larger in diameter and is stuck in the freezer to cold soak, the part that it will be inserted into is warmed (not red hot or even close, just very warm) the two slip together, but when cooled must be pressed apart.</p><p></p><p>The main point here is, that the part with the bore in it is heated and its inside diameter gets larger, not smaller as it expands. I would not disagree that the part does expand and will get thicker also, BUT its circumferance expands/increases way "more" which creates the larger ID.</p><p></p><p>When freezing a shaft/race/bushing etc to be placed into a bore its circumferance "shrinks" a small amount, enough that if the interferance fit between part is small enough it will slip into the bore or be tapped in very easily... if done quickly.</p><p></p><p>Most fluting I've seen done were with even numbers of flutes so that the raised portion between flutes opposed each other, to retain the original barrel's OD stiffness but reduce weight. Stiffness would "not" be retained if a ridge was opposed by a flute and not another ridge. A barrel's stiffness can't be increased by fluting but it can be reduced in weight and retain original rigidness. Much like a steel "I" beam or "H" beam.</p><p></p><p>IMO a bore will change dimensionally when fluting because of the heat generated during the milling process. The less heat the less change... use lots of coolant and take light cuts. Now, if the barrel will warp when heating up depends on alot of things. Who knows how much stress is already in the barrel when you get it, or if it is symmetrical or not, then how much more you add to it or releive from it isn't likely to be tested by anyone to conclusion. So, cryo treat it? Probably wouldn't hurt.</p><p></p><p>We do quite a bit of fluting, 12 and 8 sided barrels but never have tested the "before and after" accuracy. I do have my concerns about it though.</p></blockquote><p></p>
[QUOTE="Brent, post: 70037, member: 99"] LB, How do you explain a press fit/interferance fit between two cylindrical parts? The part being inserted into a bore is a couple thou larger in diameter and is stuck in the freezer to cold soak, the part that it will be inserted into is warmed (not red hot or even close, just very warm) the two slip together, but when cooled must be pressed apart. The main point here is, that the part with the bore in it is heated and its inside diameter gets larger, not smaller as it expands. I would not disagree that the part does expand and will get thicker also, BUT its circumferance expands/increases way "more" which creates the larger ID. When freezing a shaft/race/bushing etc to be placed into a bore its circumferance "shrinks" a small amount, enough that if the interferance fit between part is small enough it will slip into the bore or be tapped in very easily... if done quickly. Most fluting I've seen done were with even numbers of flutes so that the raised portion between flutes opposed each other, to retain the original barrel's OD stiffness but reduce weight. Stiffness would "not" be retained if a ridge was opposed by a flute and not another ridge. A barrel's stiffness can't be increased by fluting but it can be reduced in weight and retain original rigidness. Much like a steel "I" beam or "H" beam. IMO a bore will change dimensionally when fluting because of the heat generated during the milling process. The less heat the less change... use lots of coolant and take light cuts. Now, if the barrel will warp when heating up depends on alot of things. Who knows how much stress is already in the barrel when you get it, or if it is symmetrical or not, then how much more you add to it or releive from it isn't likely to be tested by anyone to conclusion. So, cryo treat it? Probably wouldn't hurt. We do quite a bit of fluting, 12 and 8 sided barrels but never have tested the "before and after" accuracy. I do have my concerns about it though. [/QUOTE]
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Barrel fluting post build affect accuracy?
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