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Rifles, Reloading, Optics, Equipment
Reloading
Loading to magazine length/bent tips
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<blockquote data-quote="CONatureBoy" data-source="post: 2215664" data-attributes="member: 118769"><p>Here's the SAAMI 300 RUM chamber spec:</p><p></p><p>[ATTACH=full]278815[/ATTACH]</p><p></p><p>If I read that right, it has 3.2487" - 2.9880" = 0.2607" of leade and 2.9880" - 2.8780" = 0.11" of throat. Or if I should use the inner number, that would be 2.988" - 2.860" = 0.128" of throat. By way of comparison, here's the 280 AI spec:</p><p></p><p>[ATTACH=full]278820[/ATTACH]</p><p></p><p>The throat here would be 2.754" - 2.560" = 0.194", about half again as much as the 300 RUM. So I don't see extraordinary jump in the RUM's chamber design. . . .</p><p></p><p>The Wikipedia article on the RUM concludes that it was "conceived as a long range hunting cartridge" well suited to shooting heavy/long-for-caliber bullets. Comparing it to the 30-378 Weatherby, the article says, "The .30-378 Weatherby Magnum is considered the most <a href="https://en.wikipedia.org/wiki/Overbore" target="_blank">overbore</a> production sporting cartridge available and is not considered as efficient as the .300 RUM cartridge. In part due to its excessive freebore lengths the claimed velocities by Weatherby is a resultant factor of this freebore length. If chambered to allow bullets to seat to the lands of the rifling the large Weatherby cartridges would exhibit overpressure signs immediately. All things equal the .300 RUM and .30-378 Weatherby if chambered with the same throat and freebore would be comparable." I don't know who wrote that, but it's consistent with my speculations about pressure peaking faster when you seat close to the lands. Weatherby chambers have lots of freebore to flatten out the pressure peak, so they can maintain peak pressure longer (by burning oodles of powder), to get the speed that made Weatherby famous.</p></blockquote><p></p>
[QUOTE="CONatureBoy, post: 2215664, member: 118769"] Here's the SAAMI 300 RUM chamber spec: [ATTACH type="full" alt="1623256185255.png"]278815[/ATTACH] If I read that right, it has 3.2487" - 2.9880" = 0.2607" of leade and 2.9880" - 2.8780" = 0.11" of throat. Or if I should use the inner number, that would be 2.988" - 2.860" = 0.128" of throat. By way of comparison, here's the 280 AI spec: [ATTACH type="full" alt="1623256593977.png"]278820[/ATTACH] The throat here would be 2.754" - 2.560" = 0.194", about half again as much as the 300 RUM. So I don't see extraordinary jump in the RUM's chamber design. . . . The Wikipedia article on the RUM concludes that it was "conceived as a long range hunting cartridge" well suited to shooting heavy/long-for-caliber bullets. Comparing it to the 30-378 Weatherby, the article says, "The .30-378 Weatherby Magnum is considered the most [URL='https://en.wikipedia.org/wiki/Overbore']overbore[/URL] production sporting cartridge available and is not considered as efficient as the .300 RUM cartridge. In part due to its excessive freebore lengths the claimed velocities by Weatherby is a resultant factor of this freebore length. If chambered to allow bullets to seat to the lands of the rifling the large Weatherby cartridges would exhibit overpressure signs immediately. All things equal the .300 RUM and .30-378 Weatherby if chambered with the same throat and freebore would be comparable." I don't know who wrote that, but it's consistent with my speculations about pressure peaking faster when you seat close to the lands. Weatherby chambers have lots of freebore to flatten out the pressure peak, so they can maintain peak pressure longer (by burning oodles of powder), to get the speed that made Weatherby famous. [/QUOTE]
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