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One of Us |
does anyone have a program that can easily calculate the capacity of this case below; base dia. .411 shld dia. .360 shld length 1.68 case length 2.28 calibre .244 neck length .296 shld angle 8 1/2 deg. | ||
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One of Us |
41 gr. I used the thickness of .308 brass so your capacity might be different depending on the thickness of the brass used. Whats up with that shoulder angle? | |||
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One of Us |
Hello Bigfoot, Thanks for the calculation. The dimensions I gave you are of the .300H&H reduced by 20% allover. I rounded afew numbers off a little, but only by a thou or two. So that 8 1/2 deg. may be ever so slightly out. | |||
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one of us |
I wrote up a basic case capacity calculator a while back. It's here, and it requires no download, the math being handled by the browser. The analysis isn't so complete as that offered by Big-foot, but it gets you in the ball park. I entered your numbers and assumed a case weight of 155 gn, a bit heavier than the .30-30's I've weighed. It came up with a bit under 41 gn. By the way, if you cube your 80% scaling and multiply by the case volume of the .300 H&H, you have 86 * 0.80^3 = 44.0 gn. Now, the brass walls don't scale so thin, so take a bit off the case capacity and you're back near 41 gn. If you know the weight of .300 brass, you can roughly scale it down using the ratio 0.80^2 and improve your estimate. That's 80% for the reduced girth and another 80% for the reduced length, and the same ratio for the reduced area of the base. I don't have the case weight of the .300, but I know RWS 9.3x74R brass is about 220 gn. This case is the correct length, but the diameter is about 9% (and thus the girth) too small. Applying this to the 9.3 case, I get 240 gn, and call it 250 gn to compensate for the bigger area of the base. Apply the 0.80^2 factor to this 250 gn and you get 160 gn, in line with the 155 gn rough estimate of above. The first estimate, using 0.80^3, would have made the brass too thin, at about 250 * 0.80^3 = 128 gn. The correction is 160-128 or 32 gn. Each 8.5 gn of brass displaces 1.0 gn of water, so the estimate of 44.0 gn water become 44.0 - 32/8.5 = 40.3 gn. Anyway, all this math isn't to show you I can use a calculator, but instead to show that fair estimates can be made with simple tools. | |||
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