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What is the capacity of this case?
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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.
 
Posts: 2134 | Registered: 12 May 2005Reply With Quote
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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?
 
Posts: 116 | Registered: 27 January 2005Reply With Quote
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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.
 
Posts: 2134 | Registered: 12 May 2005Reply With Quote
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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.
 
Posts: 980 | Location: U.S.A. | Registered: 01 June 2003Reply With Quote
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