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March 24, 2010, 11:54 PM
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#1 |
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Senior Member
Join Date: November 12, 2008
Location: Fort Worth, TEXAS
Posts: 909
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Calculating the VMD of a particular powder
I am using a Lee Pro Auto Disk PM. I just bought some N105 and Longshot. Neither one of these powders are listed in the chart that came with my powder measure.
Short of trial and error with my disks, or finding a hollow cube that is exactly 1 cc, how can I find the VMD of these two powders? |
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March 25, 2010, 12:07 AM
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#2 | |
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Senior Member
Join Date: June 10, 2004
Location: Tioga co. PA
Posts: 2,647
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Can't help you with the N105 but 1cc of longshot is 12.1 gr.
can you do the math from there? Quote:
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USNRET '61-'81 |
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March 25, 2010, 12:10 AM
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#3 |
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Senior Member
Join Date: November 12, 2008
Location: Fort Worth, TEXAS
Posts: 909
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Yes, thank you.
Where did you get that information? |
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March 25, 2010, 12:32 AM
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#4 |
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Staff
Join Date: April 14, 2000
Location: Northern Virginia
Posts: 41,642
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It's simple, really.
Take the disk with the hole closest to 1 cc. Throw several charges, and weigh them. A little simple math will give you the approximate number of grains per CC.
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"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza Baby Jesus cries when the fat redneck doesn't have military-grade firepower. |
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March 25, 2010, 12:38 AM
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#5 |
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Senior Member
Join Date: November 12, 2008
Location: Fort Worth, TEXAS
Posts: 909
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Yeah, I was looking for a disk that was 1cc, but there wasnt one. I think .93 and 1.07 was the closest?
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March 25, 2010, 01:10 AM
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#6 |
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Senior Member
Join Date: December 10, 2005
Location: Central , OR
Posts: 1,888
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http://www.tacticoolproducts.com/powder.pdf
This may help. |
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March 25, 2010, 09:05 AM
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#7 | |
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Senior Member
Join Date: June 10, 2004
Location: Tioga co. PA
Posts: 2,647
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Quote:
There is a "slide rule" that comes with a box of Lee dippers. NOTE: this value will be approximate and is usually on the light side. It's published data and Lee tends to do that to insure you won't get an overcharge. In the end you will need to fish to the correct hole to get the charge you want. Using the VMD method will get you close.
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USNRET '61-'81 |
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March 25, 2010, 10:03 AM
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#8 |
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Staff
Join Date: April 14, 2000
Location: Northern Virginia
Posts: 41,642
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"Yeah, I was looking for a disk that was 1cc, but there wasnt one. I think .93 and 1.07 was the closest?"
That sounds about right. So use the .93 disk. You know that's 93% of 1 CC. Say that gives you 9.3 grains. An additional 7% will give you 0.651 grains, which is close enough to 7 grains to get you to the 1 cc = 10 grains.
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"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza Baby Jesus cries when the fat redneck doesn't have military-grade firepower. |
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March 25, 2010, 10:25 AM
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#9 |
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Moderator Emeritus
Join Date: June 25, 2008
Location: Austin, CO
Posts: 19,694
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It is curious why they wouldn't do a 1.0cc disk..... my set has .93 and 1.02
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March 25, 2010, 11:29 AM
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#10 |
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Senior Member
Join Date: March 22, 2008
Location: Western Colorado
Posts: 244
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My N105 has a VMD of .0917. YMMV
cc / vmd = grains (or cc / grains = vmd) Last edited by RidgwayCO; March 25, 2010 at 11:39 AM. |
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