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Rifles, Reloading, Optics, Equipment
Reloading
.338 RUM with 300gr SMK and Retumbo... over pressure?
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<blockquote data-quote="Autorotate" data-source="post: 618112" data-attributes="member: 8073"><p>Just like Broz posted....I agree...It may very well be a temp sensitivity thing with Retumbo. Actually it's my experience Retumbo and H1000 share very similar temp resilence properties, but Retumbo does go "super nova" (sometimes in as little as .5 to .75 of a grain) when you step over a certain threshold. The heat soak of the 6th or 7th round might be just enough to push you over that edge your riding with your lot of retumbo and this load with your rifle.</p><p> </p><p>I'd look at a change in velocity when shooting that "hot" 6th or 7th round, and measure the case web diameter just north of the extraction groove, and see if you don't see some correlation with pressure before you gave up on Retumbo though.</p><p> </p><p>Your post about not seeing an extractor mark, or any cratering primers is conflicting.... but you might not be seeing enough pressure for those overpressure indicators.</p><p> </p><p>Grab a chrono and a set of calipers next time your out....see if those don't point to pressure.</p><p> </p><p>If not, maybe look elsewhere....example....How much are you bumping the shoulder? What type of sizing are you doing?</p></blockquote><p></p>
[QUOTE="Autorotate, post: 618112, member: 8073"] Just like Broz posted....I agree...It may very well be a temp sensitivity thing with Retumbo. Actually it's my experience Retumbo and H1000 share very similar temp resilence properties, but Retumbo does go "super nova" (sometimes in as little as .5 to .75 of a grain) when you step over a certain threshold. The heat soak of the 6th or 7th round might be just enough to push you over that edge your riding with your lot of retumbo and this load with your rifle. I'd look at a change in velocity when shooting that "hot" 6th or 7th round, and measure the case web diameter just north of the extraction groove, and see if you don't see some correlation with pressure before you gave up on Retumbo though. Your post about not seeing an extractor mark, or any cratering primers is conflicting.... but you might not be seeing enough pressure for those overpressure indicators. Grab a chrono and a set of calipers next time your out....see if those don't point to pressure. If not, maybe look elsewhere....example....How much are you bumping the shoulder? What type of sizing are you doing? [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
.338 RUM with 300gr SMK and Retumbo... over pressure?
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