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Posted: 12/9/2015 11:58:51 PM EDT
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Started resizing FC 223 casings using Hornady's datum point case gage. Got the lot inside the size I was looking for...
Then I switch over to WCC 223 casings. The resized differently and I needed to size them down more... Good thing I checked rather than assumed that the different manufacturer would size the same. I would like to know "the why" behind the reason they sized differently. Fired from a different firearm? Different dimensions? Different brass configuration? What I know is my sizing die didn't move. Can someone help me understand why. I supposed I should recheck every time I switch base types. But what about those who throw various types into the their reloader? |
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Fired from a different firearm? Different dimensions? Yes. The die has to push the case body in on sizing, to move the shoulder forward. You would have to neck size only, for about 3 loadings, for the brass to fully expand to the chamber, to get the true head to datum measurement. The firing pin strike may set the shoulder back .006" A light load may expand the case body outward, pulling the shoulder back. Shorter head to datum measurement. |
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Quoted: Started resizing FC 223 casings using Hornady's datum point case gage. Got the lot inside the size I was looking for... Then I switch over to WCC 223 casings. The resized differently and I needed to size them down more... Good thing I checked rather than assumed that the different manufacturer would size the same. I would like to know "the why" behind the reason they sized differently. Fired from a different firearm? Different dimensions? Different brass configuration? What I know is my sizing die didn't move. Can someone help me understand why. I supposed I should recheck every time I switch base types. But what about those who throw various types into the their reloader? Different case will be a slightly different alloy, so spring back will be different. FC rifle brass is soft, I don't even use it, it's gets sold off. I use mostly Win, LC, and PMC. I check the cases for proper sizing but seldom have to change my sizing die adjustment. |
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