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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
338-408 chey-tac powders
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<blockquote data-quote="NZ Longranger" data-source="post: 463028" data-attributes="member: 14"><p>Augustus,</p><p>There's a simple little barrel life calculator that I'll see if I can post up a link to. Can't remember where I got it from. Anyway, it takes bore size, powder weight, powder heat potential and chamber pressure into account. The powders with the highest heat potential are the worst barrel burners, all else being equal. Unfortunately I haven't been able to find the exact heat potential figure for 869, but presume it to be similar to H870 which was its forerunner. It produces the same velocity for the same pressure as H870 but doesn't have the extreme temperature variability and carbon fouling issues that H870 has. </p><p>Anyway, this calculator gives 869 a 30% barrel life increase over 50BMG, and this is backed up by what we see through the bore scope down our barrels. Its takes very little time before you see significant fire cracking with 50BMG, 50 rounds and its there. By 300 rounds they look shocking, and by 500 they're pretty much gone for all money. Depends on how you shoot them of course, so some will get more, some will get way less. We have only completely shot out one 338 barrel with 50BMG, but if you ask around amongst those who've shot the 338/408 a lot, I think you'll find its the consensus of about where it sits. Be interesting to hear some other comments on this?</p><p>We've shot out plenty of big 7mm barrels with 50BMG, and have seen the same thing verses 869. Comparing like with like, we don't see the same level of fire cracking with 869 until you've fired nearly twice as many rounds. So far we've only chambered Lunatics in button rifled barrels, like Liljas, Broughtons and Trueflites. I have some Bartlien cut barrels here to try, which going by our experience with cut Kreigers in 7mm could extend the life significantly. </p><p>And in the 338 Lunatic for the same 67,500psi pressure (measured with Oehler 43 Bal. Lab, not just a guess), we get about 100 fps more with 869 than 50BMG. Viht 20N29 produces getting on for the same velocity for pressure as 869, and should have even better barrel life in theory due to its lower heat potential, but we haven't shot it enough to say yet. 869 is just so easy to work with, so long as you aren't getting hangfires, which is why we shortened the case 75 thou. </p><p>Greg</p></blockquote><p></p>
[QUOTE="NZ Longranger, post: 463028, member: 14"] Augustus, There's a simple little barrel life calculator that I'll see if I can post up a link to. Can't remember where I got it from. Anyway, it takes bore size, powder weight, powder heat potential and chamber pressure into account. The powders with the highest heat potential are the worst barrel burners, all else being equal. Unfortunately I haven't been able to find the exact heat potential figure for 869, but presume it to be similar to H870 which was its forerunner. It produces the same velocity for the same pressure as H870 but doesn't have the extreme temperature variability and carbon fouling issues that H870 has. Anyway, this calculator gives 869 a 30% barrel life increase over 50BMG, and this is backed up by what we see through the bore scope down our barrels. Its takes very little time before you see significant fire cracking with 50BMG, 50 rounds and its there. By 300 rounds they look shocking, and by 500 they're pretty much gone for all money. Depends on how you shoot them of course, so some will get more, some will get way less. We have only completely shot out one 338 barrel with 50BMG, but if you ask around amongst those who've shot the 338/408 a lot, I think you'll find its the consensus of about where it sits. Be interesting to hear some other comments on this? We've shot out plenty of big 7mm barrels with 50BMG, and have seen the same thing verses 869. Comparing like with like, we don't see the same level of fire cracking with 869 until you've fired nearly twice as many rounds. So far we've only chambered Lunatics in button rifled barrels, like Liljas, Broughtons and Trueflites. I have some Bartlien cut barrels here to try, which going by our experience with cut Kreigers in 7mm could extend the life significantly. And in the 338 Lunatic for the same 67,500psi pressure (measured with Oehler 43 Bal. Lab, not just a guess), we get about 100 fps more with 869 than 50BMG. Viht 20N29 produces getting on for the same velocity for pressure as 869, and should have even better barrel life in theory due to its lower heat potential, but we haven't shot it enough to say yet. 869 is just so easy to work with, so long as you aren't getting hangfires, which is why we shortened the case 75 thou. Greg [/QUOTE]
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