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Old December 11, 2011, 10:54 PM   #1
mjm
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.223/5.56 trimming & headspace

I reload for an AR15 with a JP Enterprises AR barrel. After resizing I put every case through a case gauge. I am currently processing a large amount of milsurp brass. My motorized RCBS Pro Trim, with tri-cutter head, is slow and it gave me some problems last week. I borrowed a friend's Giraurd. The Giruard trim length was slightly longer than the 1.750 in. trim length I get with my RCBS. The Giraud trimed cases measure 1.752-1.754 in.

Given the .223/5.56 headspaces on the should, what is more important consistent neck length or consistent 1.750 trim length? Please keep in mind, every case passed the case gauge.
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Old December 11, 2011, 11:41 PM   #2
Jim243
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You should send a PM to Unclenick, he uses that trimmer and would be able to answer your question better.

Jim
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Old December 11, 2011, 11:48 PM   #3
farmerboy
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First of all, I'd figure the problem out with the RCBS first the if you resized after fireforming with your gun and then trimmed with everything set correctly you shouldn't have variances. Unless you're doing something wrong. Search and you'll figure it out.
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Old December 12, 2011, 12:37 AM   #4
mehavey
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First, the Giraud bases its total trim length off of the shoulder (which is why you have to resize correctly/consistently to start with)

Second, that final neck length from the Giraud is exactly the same case-to-case (because it references the shoulder)

Third, the Girauad is adjustable to produce literally any OAL/neck you want.

As to which is more important? ...neither within the reasonable limits of either one of them.

Consistency case-to-case is by far more more important.

Last edited by mehavey; December 12, 2011 at 10:36 AM.
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Old December 12, 2011, 12:44 AM   #5
farmerboy
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Last post true, just whichever direction you go, just make sure to do the most accurate steps for each and every thing you do I'n reloading. Consistency is the key each and every time
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Old December 12, 2011, 09:37 AM   #6
mjm
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Consistency is important and root cause for the question. The case gauge helped identify resized cases that did not or would not meet spec after sizing in a FL/SB die.

I assume there is pretty decent uniformity for those cases that passed testing in the case gauge, given there is an acceptable range between too long and too short. Given the few thousandths between go/no-go I should have expected minor differences in the trim length when registering off the shoulder. I accept I will probably never see any measureable differences when firing these rounds in an AR, but was curious regardless. It seemed to me the Giraurd will give the best possible consistency.
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Old December 12, 2011, 10:00 PM   #7
jepp2
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I'm not exactly sure how you are using your gage, so I'm not sure what you are looking at.

You know the maximum case length is 1.760". You also know the trim to length is 1.750" (unless you are using an RCBS X die). I feel the 0.010" range isn't significant to the consistency of performance. So I don't spend much time worrying about that. If you are crimping, the length difference can make more of an impact.

I feel things like neck and bullet concentricity impact accuracy more. So are you lubing your necks to reduce the potential for the expander to pull the neck off line? I use a carbide expander button to make that part of the sizing step easier on the case. There are steps you can take to make your bullet seating more concentric without even going to the premium bullet seating dies.

Just trying to make sure you consider there are more things that can impact the end result.
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Old December 14, 2011, 08:39 PM   #8
mjm
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Thanks guys. The Giraurd could have been adjusted to give me the same length as the other. I am strongly considering getting one.

Quote:
I'm not exactly sure how you are using your gage, so I'm not sure what you are looking at.
I followed these guidelines:
http://www.dillonhelp.com/xl650english2/pg29.htm

Quote:
neck and bullet concentricity impact accuracy more
You got me thinking while I put away the sizing die. I examined the die and found the expander was not exactly centered. I will have to order a new one.
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Old December 14, 2011, 09:04 PM   #9
mehavey
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Quote:
The Giraurd ...am strongly considering getting one.
It's the greatest thing since sliced bread.
You'll never look back....
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