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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Cold bore mapping?
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<blockquote data-quote="Litehiker" data-source="post: 1113050" data-attributes="member: 54178"><p>POI CHANGE, COLD BORE SHOTS, CLEAN BORE SHOTS & BARREL STRESS</p><p></p><p>POI CHANGE can happen for several reasons (other than shooter error)</p><p>Barring moisture in the barrel, more than 10 F. temperature changes, ammunition lot differences, etc. then you may have a stressed barrel. Consumer testing for this is likely best done from a rifle clamp/cradle like a Lead Sled that holds the rifle in place so the only part of the rifle touched by the shooter is the trigger, and that always in a consistent, straight back direction.</p><p>EX. If your Clean Cold Bore AND Dirty Cold Bore shots are pretty much in the same POI while Warmup-up shots group differently, especially OFF VERTICAL AXIS, then your barrel could shift POI due to manufacturing stress in the barrel that appears once it gets warm.</p><p></p><p>The usual "cures" for this are either cryogenic treatment or a new barrel. I have a suspicion that Bartlein barrels may be so good because they test barrels for inherent stress and in some way can separate stressed barrels from the rest OR have discovered how to make "unstressed" barrels. This latter method may be the answer.</p></blockquote><p></p>
[QUOTE="Litehiker, post: 1113050, member: 54178"] POI CHANGE, COLD BORE SHOTS, CLEAN BORE SHOTS & BARREL STRESS POI CHANGE can happen for several reasons (other than shooter error) Barring moisture in the barrel, more than 10 F. temperature changes, ammunition lot differences, etc. then you may have a stressed barrel. Consumer testing for this is likely best done from a rifle clamp/cradle like a Lead Sled that holds the rifle in place so the only part of the rifle touched by the shooter is the trigger, and that always in a consistent, straight back direction. EX. If your Clean Cold Bore AND Dirty Cold Bore shots are pretty much in the same POI while Warmup-up shots group differently, especially OFF VERTICAL AXIS, then your barrel could shift POI due to manufacturing stress in the barrel that appears once it gets warm. The usual "cures" for this are either cryogenic treatment or a new barrel. I have a suspicion that Bartlein barrels may be so good because they test barrels for inherent stress and in some way can separate stressed barrels from the rest OR have discovered how to make "unstressed" barrels. This latter method may be the answer. [/QUOTE]
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Cold bore mapping?
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