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FL Sizing Question

This is a discussion on FL Sizing Question within the Ammunition forums, part of the M14 M1A Forum category; I decided to adjust my sizing die for my M1A to bump the shoulder back .003-.005 and started by sizing a case then turning the ...


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Old May 11th, 2017, 09:10 AM   #1
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FL Sizing Question

I decided to adjust my sizing die for my M1A to bump the shoulder back .003-.005 and started by sizing a case then turning the die down a little more and sizing another case until i got one that would allow my disassembled bolt to close easily on it. I put that one in my case gauge to verify i was in spec. and then set the bump back with my Hornady comparator from there. It worked well with a batch of LC cases.I checked them all in my case gauge and with my chamber and bolt. When i switched headstamps to WCC almost none would allow my bolt to close on it own. if i let it go with some spring pressure it would close. I thought the die would form the same outside dimensions on any case, anybody ever run into this? I was hoping to reduce stretch on my brass but dont want the risks of slamfire. if i have to adjust my dies for each headstamp i will just go back to a cam over setting. It is a standard RCBS FL die with a Lyman carbide expander in it. Thanks for the help.

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Old May 11th, 2017, 11:59 AM   #2
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I separate cases by headstamp before resizing for this reason. Different makers, slight variations in manufacture.

I usually need to make very slight adjustments in the amount of cam-over for different brands.

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Old May 11th, 2017, 12:59 PM   #3
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I thought the die would form the same outside dimensions on any case, anybody ever run into this?
When the ram is all the way up, the brass in the die is all the same specification.

After you remove the brass from the sizing die, it is no longer under the pressure of sizing and will have "sprung back" to larger dimensions (just like a spring).

Different kinds of or manufactures of brass have different amounts of spring back.

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Old May 11th, 2017, 01:00 PM   #4
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If you push the WCC case into the chamber firmly with your thumb, will the stripped bolt then close?

Or maybe just lower the resize die ~ 1/16 of a turn and see if that works.

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Old May 11th, 2017, 02:36 PM   #5
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No if i push it in the chamber it still doesnt close on its own. But i can push the op rod handle closed without a lot of pressure. When i open the bolt i can easily remove the case with my fingernail.

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Old May 11th, 2017, 04:01 PM   #6
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No if i push it in the chamber it still doesnt close on its own. But i can push the op rod handle closed without a lot of pressure. When i open the bolt i can easily remove the case with my fingernail.
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If it was ME, I'd just lower the resize die a tiny amount and call it good.

The IMPORTANT thing is that the bolt rotates fully closed when a new cartridge is chambered.

Also use a 'chamber cleaning tool' to clean the chamber - a patch on a bore rod usually isn't enough to thoroughly clean the shoulder area in the chamber.

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Old May 11th, 2017, 04:07 PM   #7
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Thanks Jay!

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