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Old May 13, 2002, 03:29 PM   #1
Poodleshooter
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Join Date: August 7, 2000
Location: Floating down the James River in VA
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case weight in relation to case capacity

Over the weekend, I conducted an inpromptu test with some .308 brass that I had primed. I weighed 5 cases of 3 different headstamps (Remington, Hirtenberger and Federal). All 15 cases had been sized, trimmed and primed at the same time. I weighed and recorded each case, then filled them to the brim with the finest powder I had (WC846) to eliminate powder arrangement variations. I then weighed each cases powder capacity. There was definite consistency to each headstamp's relative case weight. The extreme spread over this ridiculously small sample was only about 2-3 grs per headstamp. The ES between the brands revealed that the lightest cases (Hirtenberger) were about 5-10 grs lighter than the average Remington, which were nearly 20grs lighter than the average Federal match brass. Now for the odd part. The case capacity of the Remington and Hirtenberger overlapped. They were for all purposes of this sample-identical in case capacity, though their weight differed slightly. The ES between the 2 groups was about .5grs of capacity. The Federal brass, oddly enough, had a MUCH HIGHER capacity despite the heavier brass. There was nearly a 2-3gr difference in powder capacity as compared to the other 2 headstamps.
(Note: This "data" is via recollection of my results, as I am not in proximity to my notes.)
So, despite the ridiculously small sample that only bears any importance to my own personal batches of ammo, I have to come to a conclusion that case weight means little when compared to actual internal volume, though of course, consistent case weight would still lead to consistent capacity.
According to this test, I'm going to try treating the Hirtenberger and Remington cases identically, and see if the groups or velocity consistency suffer with known loads, or if they are functionally identical.
Anybody else run little tests like this?
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Old May 13, 2002, 06:55 PM   #2
C.R.Sam
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Join Date: October 29, 1999
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Sumpin that'll put a wiggle in the road is actual loacation, depth and width of extractor groove. And tiny weight differences between different formulations of brass per unit of cubic measure. And flash hole diameter.

All cases from same lot helps.

Sam.....pick nitty.
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