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Posted: 11/13/2009 2:36:30 PM EDT
| After resizing my brass on my Dillon 550 my brass seems to be growing a few thousanths of an inch is this normal ? |
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It's normal when the inside of the case mouth is not lubed.
The expander ball pulls the case shoulder out when it's withdrawn, undoing part of the sizing operation. Carbide expander balls help alleviate this problem. If you're using Dillon dies, I don't know if a carbide ball is available for them. If the case mouths are round and the cases already decapped, the expander ball and decapping pin can be removed from the die while sizing. |
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In addition to the above post, which has maret, a funcrion of resizing (moving the case metal) causes the metal to extrude forward.
The neck diameter is reduced by a few thousandths. That accounts for case increase in length from as measured length before resizing. |
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Quoted:
In addition to the above post, which has maret, a funcrion of resizing (moving the case metal) causes the metal to extrude forward. The neck diameter is reduced by a few thousandths. That accounts for case increase in length from as measured length before resizing. You're right and I shouldn't have overlooked that effect. This is the reason we trim brass after sizing. So, what that means the shoulder can be in the right place, but the case too long. A case gage will sort this out. I've gotten too accustomed to the threads about cases that were too long for a fixed drop in gage, or got stuck in a chamber. Sometimes they're longer because metal was moved into the case neck during sizing. |
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