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Post by willbird on Dec 21, 2012 11:01:35 GMT -5
I love spreadsheets...so I hacked one up to show the length of powder chamber required for a given weight of powder if you know the VMD (they are listed in Dick Lee's book, or the instructions for the Lee Perfect powder measure) and the dia of the bore or powder chamber. The VMD times the powder weight in grains gives you the CC's of powder chamber needed to dispense that charge with very little compression. As an example I calculated the powder column length of 77.0 grains of Varget with little or no compression at 2.748 inches in a .500 bore/powder chamber. If we alter the dia to .412 the powder column becomes 4.047" long.
Maybe I am duplicating something somebody already did.....but if anybody would like the spread sheet to play with, PM me....I have it in .odf format (open office) but should be able to convert it to excel.
For bore sizes with no powder chamber I think it would come out close to use the average between land and groove dia ??
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Post by willbird on Dec 21, 2012 11:11:28 GMT -5
OK was able to convert to excel.
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Post by willbird on Dec 21, 2012 11:14:14 GMT -5
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Post by willbird on Dec 21, 2012 11:17:45 GMT -5
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Post by fishhawk on Dec 21, 2012 11:19:03 GMT -5
The Lee data is where I started. I kept my chamber shorter than what I expected not knowing for sure how much it would compress when the bullet is seated, and how much of what powder I would end up with. I can cut more out easier than putting it back in! I remember calculating that 55gr of a forgotten powder was something like 1.9" in a standard .416 bore, but was 1.3" in a .5" chamber. It's in the forum somewhere under somthing I posted.
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Post by willbird on Dec 21, 2012 12:16:48 GMT -5
For sure it is more difficult to put metal back than it is to take it away
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Post by edge on Dec 21, 2012 12:19:24 GMT -5
You can attach the spreadsheet directly from your computer without offshore hosting. click on the Attachment "box" between the subject and the Message Icon and choose your file. You may have to read the Attachment Agreement first  edge. |
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Post by willbird on Dec 21, 2012 16:52:53 GMT -5
Thanks Edge :-) OK lets give it a whirl :-). Attachments:
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Post by willbird on Dec 21, 2012 19:21:58 GMT -5
Got a question by PM about a .375 bore and 75 grains of IMR 4350. At zero compression I got 4.888 as the answer with a .371 dia (average of major and minor dia's). For a .500 powder chamber I got 2.763".
Bill
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Post by willbird on Dec 21, 2012 19:36:18 GMT -5
Ok I cleaned the spreadsheet up a bit, and protected some cells, should make it easier to use. There are 3 identical sections to allow you to compare different things if you wish. Attachments:
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Post by willbird on Dec 21, 2012 19:37:23 GMT -5
Ok I cleaned the spreadsheet up a bit, and protected some cells, should make it easier to use. There are 3 identical sections to allow you to compare different things if you wish. If you want to alter it the password is null, just leave the box blank |
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Post by AJ on Dec 22, 2012 10:24:09 GMT -5
With Excel 2010 the formulas do not show up. Just the text boxes with values.
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Post by willbird on Dec 22, 2012 16:58:57 GMT -5
With Excel 2010 the formulas do not show up. Just the text boxes with values. I protected the sheet to make it look a little less complicated.....some cells are hidden.....if you unprotect the sheet ( password is null....just leave it blank) those cells will reappear . The earlier file is not protected. |
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Post by willbird on Jan 12, 2013 8:17:24 GMT -5
Man I totally somehow hacked up the spreedsheet, some kind of flashback or late night boo-boo...this one might work better. Attachments:
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