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Rifles, Reloading, Optics, Equipment
Reloading
Revisiting: sorting cases by weight
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<blockquote data-quote="ShtrRdy" data-source="post: 1659969" data-attributes="member: 40852"><p>I've been doing a little experiment with some new Lapua brass for the .308 Win. I had weighed the 100 cases in the box and measured a spread of 3.2 grain. I thought this was a little large for Lapua so I wrote the customer service and they told me that their manufacturing strives to obtain a close case capacity and the case weight can vary.</p><p></p><p>So I took three cases on the low weight end and three cases on the high weight end and fired them. Then I measured the fired case weight and filled it with water. I then measured the case plus water weight and subtracted off the empty fired case weight. </p><p></p><p>The first time I did this, ( new brass ), I came up with the following:</p><p>Lite brass H20 weight = 55.8, 55.6, 55.7</p><p>Heavy brass H20 weight = 55.4, 55.5, 55.5</p><p></p><p>I repeated this test using the same pieces of brass but this time they are once fired.</p><p>Lite brass H20 weight = 55.7, 55.6, 55.7</p><p>Heavy brass H20 weight = 55.3, 55.4, 55.3</p><p></p><p>The second time I performed the test I measured the velocity of the load I was using. This comprised of a CCI Large Rifle primer, 175 Sierra Matching and 41.5 gr IMR-4064.</p><p>Lite brass load velocity = 2576, 2590, 2599</p><p>Heavy brass load velocity = 2603, 2601, 2598</p><p></p><p>There is some difference between these cases but aside from the velocity of 2576, not too much. It's interesting the velocity measurements on the "heavy" cases were very close to each other and that there was a bit of a spread in the velocity measurements on the "lite" cases.</p><p></p><p>I don't know if this relationship would apply to other brands of brass. I thought I had run experiments in the past by just loading and firing "lite" and "heavy" brass loads across a chronograph and would see a significant difference in velocity.</p></blockquote><p></p>
[QUOTE="ShtrRdy, post: 1659969, member: 40852"] I've been doing a little experiment with some new Lapua brass for the .308 Win. I had weighed the 100 cases in the box and measured a spread of 3.2 grain. I thought this was a little large for Lapua so I wrote the customer service and they told me that their manufacturing strives to obtain a close case capacity and the case weight can vary. So I took three cases on the low weight end and three cases on the high weight end and fired them. Then I measured the fired case weight and filled it with water. I then measured the case plus water weight and subtracted off the empty fired case weight. The first time I did this, ( new brass ), I came up with the following: Lite brass H20 weight = 55.8, 55.6, 55.7 Heavy brass H20 weight = 55.4, 55.5, 55.5 I repeated this test using the same pieces of brass but this time they are once fired. Lite brass H20 weight = 55.7, 55.6, 55.7 Heavy brass H20 weight = 55.3, 55.4, 55.3 The second time I performed the test I measured the velocity of the load I was using. This comprised of a CCI Large Rifle primer, 175 Sierra Matching and 41.5 gr IMR-4064. Lite brass load velocity = 2576, 2590, 2599 Heavy brass load velocity = 2603, 2601, 2598 There is some difference between these cases but aside from the velocity of 2576, not too much. It's interesting the velocity measurements on the "heavy" cases were very close to each other and that there was a bit of a spread in the velocity measurements on the "lite" cases. I don't know if this relationship would apply to other brands of brass. I thought I had run experiments in the past by just loading and firing "lite" and "heavy" brass loads across a chronograph and would see a significant difference in velocity. [/QUOTE]
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Revisiting: sorting cases by weight
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