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Hunting
The Basics, Starting Out
Barrel burnout
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<blockquote data-quote="Hugnot" data-source="post: 2544994" data-attributes="member: 115658"><p>This sort of indicates why my 6mm-06 quit before my 6mm Creedmoor.</p><p></p><p>[ATTACH=full]369937[/ATTACH]</p><p></p><p>From Accurate Shooter</p><p></p><p>"Looking at those two factors, we can express the 'Overbore Index' as a mathematical formula — the case capacity in grains of water divided by the area (in square inches) of the bore cross-section. This gives us an Index which lets us compare various cartridge designs."</p><p></p><p>My thinking is:</p><p></p><p>Lots of short duration but intense heat combined with particle blasting like primer & powder residues - heat, oxidation & some abrasion in an acidic environment from burning nitrates. The 6mm -06 required 4-6 minutes between shots at 45 F to group within 1 moa at 300 and that was only for the first 5-7 shots - like look at birds & stuff thru binocs waiting for barrel to cool. Enough to erode 416R stainless. An index value of 900 should be good for barrel wear, over 1000 not so good - from Accurate Shooter. The erosion is evident from removed barrel steel. The spread sheet ^ makes no provisions for different powder burn temps. The igniton temp for any carbon is 1292 deg F, at that point any carbon would be transformed into carbon dioxide. Internal surface barrel temps would exceed that but would be of extremely short duration. The chrome in stainless steel forms an oxide that is protective, like chrome oxide that coats internal surfaces.</p><p></p><p>I like to use foaming bore cleaner followed by nylon brushing with a light viscosity synthetic motor oil & JB when cleaning rifles. Carbon, if present, is insoluble, including strong acids. Clean up any residual motor oil with 91% isopropyl alcohol when done for that 1st shot thru a clean bore. Increased heat would increase pressure & velocity.</p><p></p><p>[ATTACH=full]369948[/ATTACH]</p></blockquote><p></p>
[QUOTE="Hugnot, post: 2544994, member: 115658"] This sort of indicates why my 6mm-06 quit before my 6mm Creedmoor. [ATTACH type="full" alt="Screenshot (387).png"]369937[/ATTACH] From Accurate Shooter "Looking at those two factors, we can express the 'Overbore Index' as a mathematical formula — the case capacity in grains of water divided by the area (in square inches) of the bore cross-section. This gives us an Index which lets us compare various cartridge designs." My thinking is: Lots of short duration but intense heat combined with particle blasting like primer & powder residues - heat, oxidation & some abrasion in an acidic environment from burning nitrates. The 6mm -06 required 4-6 minutes between shots at 45 F to group within 1 moa at 300 and that was only for the first 5-7 shots - like look at birds & stuff thru binocs waiting for barrel to cool. Enough to erode 416R stainless. An index value of 900 should be good for barrel wear, over 1000 not so good - from Accurate Shooter. The erosion is evident from removed barrel steel. The spread sheet ^ makes no provisions for different powder burn temps. The igniton temp for any carbon is 1292 deg F, at that point any carbon would be transformed into carbon dioxide. Internal surface barrel temps would exceed that but would be of extremely short duration. The chrome in stainless steel forms an oxide that is protective, like chrome oxide that coats internal surfaces. I like to use foaming bore cleaner followed by nylon brushing with a light viscosity synthetic motor oil & JB when cleaning rifles. Carbon, if present, is insoluble, including strong acids. Clean up any residual motor oil with 91% isopropyl alcohol when done for that 1st shot thru a clean bore. Increased heat would increase pressure & velocity. [ATTACH type="full" alt="IMG_1703 (2).JPG"]369948[/ATTACH] [/QUOTE]
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