Thread: Sizing Question
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Old November 8, 2011, 08:50 AM   #4
F. Guffey
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Join Date: July 18, 2008
Posts: 2,318
“His fired cases measure +.008 on avg. (same cases, his rifle, same factory load)”

You have everything in front of you, I do not know how you are measuring case length, if you are measuring the case length as in from the head of the case to the mouth of the case I would say we are taking about a case trimming issue, however; if you are finding the additional .008 is between the head of the case and the shoulder you may want to consider refraining from full length sizing, I apply the ‘leaver policy’ when the shoulder of my cases mover forward .008 thousands I ‘leaver out there’. I have the advantage, I use the companion tool to the press, the feeler gage, the feeler gage is the reason jump back, snap back or spring back does not lock me up.

As to the .008, or put another way, when the chambers effect on the case when fired results in an increase of .008 thousands additional length between the head of the case and shoulder I adjust the die off the shell holder with the feeler gage, first I would attempt chambering the fired cases, if the violence of being fired and being ripped from the chamber before the case was ready had an adverse effect on the case as in stretching and expanding the case will not chamber in the chamber it was fired in (without effort).

If the case chambers with a crush/interference fit use the feeler gage to adjust the die off the shell holder to prevent excessive sizing, I would start at .005 thousands, after sizing a case with the .005 thousands gap I would again attempt chambering the sized case, if the sized case chambers, I would then increase the gap to .007, I would continue this process until the press, die and shell holder had no effect on sizing the case.

In the prefect world the effect the chamber had on the fired case would be .005 thousands if the case was the prefect minimum length/full length sized, so your friend should consider his chamber is beyond go-gage length and shorter than no go-gage length, and that goes back to the ‘big inning’ M1 Garands used the same ammo as the 1903/A3 and M1917, the M1 Garand chamber had additional clearance, then there is the small base die, something reloader must have? If only they could learn to determine the length of the chamber before firing.

F. Guffey

Last edited by F. Guffey; November 8, 2011 at 09:03 AM. Reason: move ;
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