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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Big Seven Case Capacities
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<blockquote data-quote="Len Backus" data-source="post: 29879" data-attributes="member: 1"><p>Brent</p><p></p><p>I know that Mr. Bifurcated's barrel length is 32 inches, what is yours? I am planning a 34 inch barrel this time. STL's is 32 and if we are ever seen together I want to have a "bigger one" than he does. Size does matter, you know. By the way, you should see the shape of the brake on the end of his thing. Its diameter is larger than the end of the barrel and its shape is like a.....no, I can't say in public!</p><p></p><p></p><p>The Hogdon online reloading data indicates that the 300 Rum gains about 200 fps when going from a 220 caliber bullet down to a 190 grain (same pressure). That's in a short barrel. I don't know if a longer 32 inch one would show a larger or smaller difference. The Hogdon data shows about a 200 fps difference between 175 grain bullet velocities 7mm vs 30 cal.</p><p></p><p>So that would suggest adding 200 FPS to STL's 3,300 with the 210 grain bullet when working up a 180 grain load. And then drop 200 fps when switching to the 7 RUM pipe size. Resulting in 3,300 fps for a 7 Lapua with 32 inch barrel and the 176 grain Cauterucio bullet. Add about 40 to 50 fps for my 34 inch barrel for a total of 3,350 fps. So, 3,400 may be pushing it a little.</p><p></p><p>Incidentally, Hogdon doesn't sell H870 anymore and they warn that any H870 being sold today by others may not match Hogdon's data for H870.</p><p></p><p>STL</p><p></p><p>That's interesting about chronograph brand velocity reading differences. I know Oehler is supposed to be the most consistent but I never would have expected that much difference.</p><p></p><p>[ 12-14-2003: Message edited by: Len Backus ]</p></blockquote><p></p>
[QUOTE="Len Backus, post: 29879, member: 1"] Brent I know that Mr. Bifurcated's barrel length is 32 inches, what is yours? I am planning a 34 inch barrel this time. STL's is 32 and if we are ever seen together I want to have a "bigger one" than he does. Size does matter, you know. By the way, you should see the shape of the brake on the end of his thing. Its diameter is larger than the end of the barrel and its shape is like a.....no, I can't say in public! The Hogdon online reloading data indicates that the 300 Rum gains about 200 fps when going from a 220 caliber bullet down to a 190 grain (same pressure). That's in a short barrel. I don't know if a longer 32 inch one would show a larger or smaller difference. The Hogdon data shows about a 200 fps difference between 175 grain bullet velocities 7mm vs 30 cal. So that would suggest adding 200 FPS to STL's 3,300 with the 210 grain bullet when working up a 180 grain load. And then drop 200 fps when switching to the 7 RUM pipe size. Resulting in 3,300 fps for a 7 Lapua with 32 inch barrel and the 176 grain Cauterucio bullet. Add about 40 to 50 fps for my 34 inch barrel for a total of 3,350 fps. So, 3,400 may be pushing it a little. Incidentally, Hogdon doesn't sell H870 anymore and they warn that any H870 being sold today by others may not match Hogdon's data for H870. STL That's interesting about chronograph brand velocity reading differences. I know Oehler is supposed to be the most consistent but I never would have expected that much difference. [ 12-14-2003: Message edited by: Len Backus ] [/QUOTE]
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