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Discussion Starter #1
Using the empty 9mm case method. Fired case measures 2.095" and o.d. measures .421" @ .280" above the base. A case resized in my RCBS SB die measures 2.092" and base measures .417" @ .280" above the base and .418" below that. A new SSA case measures 2.097" and .417" at max o.d.. My question is this...is my sb die affecting my accuracy and case life by pushing the shoulder back shorter than a new case? Should I look into getting a fl sizing die? Thanks.
 

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Using the empty 9mm case method. Fired case measures 2.095" and o.d. measures .421" @ .280" above the base. A case resized in my RCBS SB die measures 2.092" and base measures .417" @ .280" above the base and .418" below that. A new SSA case measures 2.097" and .417" at max o.d.. My question is this...is my sb die affecting my accuracy and case life by pushing the shoulder back shorter than a new case? Should I look into getting a fl sizing die? Thanks.
Headspace gauges are quite precise instruments...

Although the 9mm method may be the "poor mans" headspace gauge, I question its accuracy...

But, that's just me...

Good-luck...bCB
 

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Something sounds screwy with your measurements all of the new SSA brass I have measured is .010-.011" under my rifles headspace in two rifles barrels from two different barrel manufactures. If you don't trust the method you are using now you could back your die out size a case and see if it will chamber if not adjust the die in at small increments until it CHAMBERS easily or with slight resistance then turn it in 1/16 of a turn and live with it.

Or get a headspace comparator set.
 

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Something sounds screwy with your measurements all of the new SSA brass I have measured is .010-.011" under my rifles headspace in two rifles barrels from two different barrel manufactures. If you don't trust the method you are using now you could back your die out size a case and see if it will chamber if not adjust the die in at small increments until it CHAMBERS easily or with slight resistance then turn it in 1/16 of a turn and live with it.

Or get a headspace comparator set.
Agree...

BCB
 

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The shoulder bump is set by the user not the die type. You have control on how much shoulder bump there is by how much you screw the die in.

As for the accuracy question the amount of bump isn't as important as powder charge consistency, and consistent neck tension. Reasoning for minimal shoulder bump is to reduce brass wear and increase brass life, not saying it doesn't play a factor just not as much as you may think.

The difference between SB and FL dies is how much the body of the case is sized too.
 

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WASSMAN;670086 Reasoning for minimal shoulder bump is to reduce brass wear and increase brass life said:
I was under the impression setting the shoulder bump was primarily for proper head-spacing.

Not sharpshooting, just a new reloader looking for info
 

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Discussion Starter #8 (Edited)
So the headspace comparator kit has a specific insert for measuring the 6.8 case at the datum? Perhaps I should get a l.e. wilson case gauge? I just suspect that my sizing die is making the case smaller than it needs to be, only reason I'm asking.

I have the Hornady bullet comparator set. I measured two places on the shoulder, using the .35" and .37" i.d. inserts. My sized case is .004" shorter than a new SSA case.....I ask, am I sizing my case too much with this die?
 

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So the headspace comparator kit has a specific insert for measuring the 6.8 case at the datum? Perhaps I should get a l.e. wilson case gauge? I just suspect that my sizing die is making the case smaller than it needs to be, only reason I'm asking.
The headspace guage has a specific insert for different sized cases or necks. It is not necessarily caliber specific. It is just a comparator. Techically, there are two different ones that are both close to the datum and either will work just as well as long as you always use the same one. A 9mm case will work fine as long as you use the same 9mm case each time and hold it perfectly straight so you get a consistent measurement.
If your die is making the case shorter than you want then back the die out a little. Also there is a difference in the bullet comparator and the headspace kit. It is a different set of inserts. One if for measuring the overall lenght of the loaded cartridge. The other if for measuring to the datum line of the case neck for setting headspace to your chamber.
 

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Discussion Starter #11
Thanks. I will work on backing the die off until I get the same length, using my janky method, as a new SSA case and check for chambering.
 

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So the headspace comparator kit has a specific insert for measuring the 6.8 case at the datum? Perhaps I should get a l.e. wilson case gauge? I just suspect that my sizing die is making the case smaller than it needs to be, only reason I'm asking.

I have the Hornady bullet comparator set. I measured two places on the shoulder, using the .35" and .37" i.d. inserts. My sized case is .004" shorter than a new SSA case.....I ask, am I sizing my case too much with this die?

I think some additional reading would be more helpful and review of what each tool does. Bullet comparators for bullets headspace comparator for headspace.
And the proper way to set up a die.
http://bisonballistics.com/articles/an-introduction-to-rifle-chambers

https://thecmp.org/training-tech/armorers-corner/headspace/

http://www.sinclairintl.com/GunTech/Setting-up-a-Full-Length-Sizing-Die-/detail.htm?lid=16134
 

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Like others suggested nothing beats precission equipment for measuring.
One thing that you can do quite easily too is to put one or two layers of aluminum tape on top of the shell holder.
Test it by pressing a few times and might give you 2 extra thousands.
If you are in a progressive you can but a ring like a little hat and stick at the base of the die.
Still lock the die.

With all that said I never saw a need for small base dies. never had problems with the regular dies in the 6.8 or in any of my guns in any caliber.
 

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I was under the impression setting the shoulder bump was primarily for proper head-spacing.

Not sharpshooting, just a new reloader looking for info
Yes you have to bump enough to chamber the round, but you can also easily bump more than needed to chamber and still have good ammo. Hence bump enough to chamber the round anything more bump than that is just extra brass wear.
 

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Discussion Starter #15
I guess it's what I get for asking. I didn't come up with the 9mm case idea, I just tried it and discovered I was sizing the brass more than I had suspected, using that method. I ordered case gauges for a few calibers I have.

I have some once fired brass from a new .223 barrel. I compared the length I measured using my (incorrect) .30 bullet comparator insert. I then measured a no-go gauge, it measured the same. I adjusted my .223 rem sb die to achieve .001" under the go-gauge reading, which gave me .004" shoulder bump. I do appreciate the help guys.
 

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I guess it's what I get for asking. I didn't come up with the 9mm case idea, I just tried it and discovered I was sizing the brass more than I had suspected, using that method. I ordered case gauges for a few calibers I have.

I have some once fired brass from a new .223 barrel. I compared the length I measured using my (incorrect) .30 bullet comparator insert. I then measured a no-go gauge, it measured the same. I adjusted my .223 rem sb die to achieve .001" under the go-gauge reading, which gave me .004" shoulder bump. I do appreciate the help guys.
There is nothing like using the right tools for the job. In some calibers you have a way to tune the size by using precision shellholders.
But this is not available for all calibers / head types.

http://www.midwayusa.com/product/359546/redding-competition-shellholder-set-10-17-remington-204-ruger-223-remington?cm_vc=ProductFinding

The Redding Compeition Shellholder Kit #10 consists of five shellholders in varying heights with increments of .002". Allows you to increase or decrease the case to chamber headspace without adjusting the dies. Storage box included.

 

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Using the empty 9mm case method. Fired case measures 2.095" and o.d. measures .421" @ .280" above the base. A case resized in my RCBS SB die measures 2.092" and base measures .417" @ .280" above the base and .418" below that. A new SSA case measures 2.097" and .417" at max o.d.. My question is this...is my sb die affecting my accuracy and case life by pushing the shoulder back shorter than a new case? Should I look into getting a fl sizing die? Thanks.
In general, new unfired brass should measure less than sized fired brass. Factory brass is almost always anywhere from .008-.015" shorter at the shoulder datum line because it has to fit in everything. If your SSA is actually longer starting out than a properly sized case, run those new cases through the sizer and trim as needed to match the rest. SSA is not always what it should be, and why I've never used it.

I'm assuming that if your fired case measures .095, and the sized measures .092, then you are getting the correct .003" bump so that is correct. While the 9mm case trick works, it isn't as precise as a proper headspace gauge. Save up and get the Hornady Headspace gauge kit. You'll be glad you did in the long run.
 

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Discussion Starter #20
I should be receiving my l.e. wilson case gauges today. I drove up to the new bass pro shops last night to see what all the fuss was about. I went ahead and picked up the hornady headspace kit anyway, can't have too many tools! Using the .350 insert, I measured 1.357" on a couple fired cases and 1.350" on one that I sized all the way with my rcbs sb die. So I guess all I need is a -.004" shell holder if I want to stop against the die. When you guys back the die off, do you get inconsistent lengths vs. stopping against the shell holder?
 
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