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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
confused and need help
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<blockquote data-quote="Kennibear" data-source="post: 960624" data-attributes="member: 51650"><p>You never mention the bullet weight/make.</p><p></p><p>Most people at this level own a chronograph. It takes the guess work down a couple of notches. The ES and SD data is also very helpful.</p><p></p><p> Retumbo is quite a bit faster than H50BMG. Given that the 300 RUM uses a case full (or thereabouts) of Retumbo the velocity with H50BMG will not match Retumbo without compression, and probably a lot of compressed H50BMG. Hodgdon's lists 102gr of H50BMg and 95.5gr of Retumbo for the 308 Nosler 200gr AB. The Retumbo is @ 62.5Kpsi and the H50BMG is @ 58.9Kpsi. The H50BMG is 100fps slower. Both are compressed.</p><p></p><p>In another Hodgdon's table with the Hornady 190gr SpBT max for both is:</p><p>105gr H50BMG (compressed), 3085fps, 63Kpsi</p><p>96gr Retumbo (NOT compressed), 3204fps, 62.5Kpsi</p><p></p><p>Note that H50BMG was higher pressure and 121fps slower.</p><p></p><p>Use the chronograph to solve your questions.</p><p></p><p>KB</p></blockquote><p></p>
[QUOTE="Kennibear, post: 960624, member: 51650"] You never mention the bullet weight/make. Most people at this level own a chronograph. It takes the guess work down a couple of notches. The ES and SD data is also very helpful. Retumbo is quite a bit faster than H50BMG. Given that the 300 RUM uses a case full (or thereabouts) of Retumbo the velocity with H50BMG will not match Retumbo without compression, and probably a lot of compressed H50BMG. Hodgdon's lists 102gr of H50BMg and 95.5gr of Retumbo for the 308 Nosler 200gr AB. The Retumbo is @ 62.5Kpsi and the H50BMG is @ 58.9Kpsi. The H50BMG is 100fps slower. Both are compressed. In another Hodgdon's table with the Hornady 190gr SpBT max for both is: 105gr H50BMG (compressed), 3085fps, 63Kpsi 96gr Retumbo (NOT compressed), 3204fps, 62.5Kpsi Note that H50BMG was higher pressure and 121fps slower. Use the chronograph to solve your questions. KB [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
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