Thread: Resizing issue
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Old October 23, 2012, 12:10 PM   #26
Bart B.
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Join Date: February 15, 2009
Posts: 8,927
Guffey's coment:
Quote:
If the 47 time fired case was being driven to the front of the chamber by the firing pin strike your cases would have stretched between the case head and case body, you measured case length, had you measured the length of the case from the case head to the case shoulder you could have could have determined the effect the chamber had on the case when it was fired.
I did that during the above 47 shot test. Starting out with a 1.628" case headspace in a SAAMI GO gauge chamber, firing it caused the case to have about 1.629" case headspace afterwords as well as the case length shortening a few thousandths. Full length sizing the case and setting the sized case headspace to somewhere between 1.627" and 1.628" ended up with the case length growing about 3 thousandths. At the end of each fire, size, reload and fire again the case grew about 1 thousandths in length.

Note also that the case shoulder set back a thousandth or two from firing pin impact; verified by chambering an empty primed case then firing it.

Last edited by Bart B.; October 23, 2012 at 12:51 PM.
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