#2442339 - 09/18/08 05:19 AM
Need help with a starting load
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Bunnyrunner
Campfire Regular
Registered: 08/06/03
Posts: 331
Loc: N.J./WY.
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I`ve necked down a Lazzeroni Patriot case to 264. Need a starting point. The specks are as follows:
Case capacity = 79 grns. of water to top of neck
120 grn. Barnes TSX length = 1.250
OAL= 2.810 case length 2.050
Barrel length = 26"
Any help would be greatly appreciated,
Skip
Edited by Bunnyrunner (09/19/08 04:38 AM)
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#2443364 - 09/18/08 03:10 PM
Re: Need help with a starting load
[Re: Bunnyrunner]
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Ken Howell
UOP Emeritus
Campfire 'Bwana
Registered: 12/14/00
Posts: 12613
Loc: Box 28 (17 Church St), Quemado...
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List the volume in grains of water to the mouth of the case with a slight meniscus above the mouth, and no air bells clinging to the inside of the case (rap the almost-full case to dislodge 'em, then fill it up).
_________________________
Ol' Useless
Benefactor Member, NRA
member, National Shooting Sports Foundation
Life Member, The Wilderness Society
obsolete now, soon extinct
(Ain't no tree family in my family tree!)
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#2444471 - 09/19/08 05:32 AM
Re: Need help with a starting load
[Re: Ken Howell]
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Bunnyrunner
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Posts: 331
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Ken,
I still come out with 79 grns.
I used the large balance scale at work. It measures in grams.
5.135 Grams = .065 X 79 grains
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#2446260 - 09/20/08 03:22 AM
Re: Need help with a starting load
[Re: Bunnyrunner]
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Ken Howell
UOP Emeritus
Campfire 'Bwana
Registered: 12/14/00
Posts: 12613
Loc: Box 28 (17 Church St), Quemado...
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grams × 15.432,358 = grains
You've erred somewhere. The capacity to the base of the neck can not be the same as the capacity to the mouth. The additional water in the neck may seem (and may indeed be) "negligible," but it's there, and it's not weightless.
Weigh ten empty cases — fired but not decapped or resized — first dry, then full of water to the mouth. Take the average of the ten differences in weights. Do not round-off to the nearest gram or 0.1 gram. Remember, 0.1 gram equals >1.5 grains.
Multiply this weight in grams by 15.432,358 to get the weight in grains.
When you weigh in grams for later conversion to grains, carry-out the grams weights as far as you can, and leave the rounding-off until after the conversion from grams to grains. Round-off the grains weight to the nearest 0.1 grain or even to the nearest 0.01 grain, not to the nearest 1.0 grain.
_________________________
Ol' Useless
Benefactor Member, NRA
member, National Shooting Sports Foundation
Life Member, The Wilderness Society
obsolete now, soon extinct
(Ain't no tree family in my family tree!)
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#2456708 - 09/25/08 04:52 AM
Re: Need help with a starting load
[Re: Ken Howell]
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Bunnyrunner
Campfire Regular
Registered: 08/06/03
Posts: 331
Loc: N.J./WY.
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Ken,
I did as you said, this time measuring on my powder scale, full to the mouth of the case. The average of ten cases works out to 78.67 grains.
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#2500571 - 10/14/08 08:32 PM
Re: Need help with a starting load
[Re: Bunnyrunner]
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MZ5
New Member
Registered: 10/11/08
Posts: 10
Loc: Idaho, USA
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As an alternative case capacity measurement method for anyone reading this thread in the future:
Obtain a syringe like those used for insulin injections (diabetic supply). Remove the needle (just pull it out with pliers), and you have a very nice 1cc cylinder graduated to the 1/100th of a cc. Clearly, you'll need to use more than 1 syringe-worth of water for most rifle cases, but it's not tough nor especially time consuming to do this. Still tap on the case when it's fairly full like Ken has suggested above. I disagree with the instruction to fill to a slight convex meniscus, but am willing to hear explanations as to why this is desirable rather than filling to level-full.
This method has proven repeatable for me, and avoids estimates as to water density, etc. If using QuickLOAD ballistics software, one can enter case capacity directly in cc.
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#2501022 - 10/15/08 04:43 AM
Re: Need help with a starting load
[Re: MZ5]
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Bunnyrunner
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Posts: 331
Loc: N.J./WY.
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This is exactly how I filled the cases. Works great.
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