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Long Range Hunting & Shooting
270 WSM - 170 gr EOL Berger load development
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<blockquote data-quote="Lou270" data-source="post: 1941723" data-attributes="member: 5352"><p>I'm having a 1-8 Hawk Hill put on a Kimber action. The max OAL in magazine is about 2.95. I was concerned about length of 170 VLD and did some math. Just looking at berger spec sheet, seating the end of 170 VLD bearing surface (i.e. just boat tail in case) to case mouth ends up with OAL of 3.06" for .270 WSM (1.8235 to base of neck + .407 bearing surface + .829 nose length). Every .1 deeper for .277 cal is .099cm^3. Using 14 gr powder/cm3 (H1000 density) that is 1.4gr powder or about 2% for 270WSM case. Rule of thumb is there is 4 to 1 ratio (Barsness Article) of increasing case capacity vs. velocity gain so that is ~.5% change in velocity (2.95 OAL vs 3.05 OAL). Assuming 3000 fps that is about 15 fps. I didn't see it as big deal. In any case for every .1 deeper or longer it is about 2%/15fps. Any case that was my math if somebody finds it useful. 270 WSM OAL is 2.86, not 2.944 by the way so the berger data is for non-saami chamber.</p><p></p><p>Lou</p></blockquote><p></p>
[QUOTE="Lou270, post: 1941723, member: 5352"] I'm having a 1-8 Hawk Hill put on a Kimber action. The max OAL in magazine is about 2.95. I was concerned about length of 170 VLD and did some math. Just looking at berger spec sheet, seating the end of 170 VLD bearing surface (i.e. just boat tail in case) to case mouth ends up with OAL of 3.06" for .270 WSM (1.8235 to base of neck + .407 bearing surface + .829 nose length). Every .1 deeper for .277 cal is .099cm^3. Using 14 gr powder/cm3 (H1000 density) that is 1.4gr powder or about 2% for 270WSM case. Rule of thumb is there is 4 to 1 ratio (Barsness Article) of increasing case capacity vs. velocity gain so that is ~.5% change in velocity (2.95 OAL vs 3.05 OAL). Assuming 3000 fps that is about 15 fps. I didn't see it as big deal. In any case for every .1 deeper or longer it is about 2%/15fps. Any case that was my math if somebody finds it useful. 270 WSM OAL is 2.86, not 2.944 by the way so the berger data is for non-saami chamber. Lou [/QUOTE]
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270 WSM - 170 gr EOL Berger load development
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