Fired and unfired brass--any correlation?

Winter here and cold outside. Too much time on my hands.
Anyway, I was curious about the chamber on my 223 and measured several pieces of fired and unfired for two different factory brands. Checked the case length on 10 of each for a good average. Brand x averaged 1.756 unfired and 1.759 fired for a .003 stretch. Brand y averaged 1.741 unfired and 1.746 fired. I have no way to measure shoulder expansion, if that makes any difference. I put a piece of masking tape(~.004) on a couple of the spent cases and the bolt handle closed, but I could tell it was tight. Definitely smeared the tape some.

Doers this tell me anything at all regarding chamber tightness or sloppiness, or is it meaningless info?
And I already know I am ocd.

Interesting information for sure. I would like to see a larger sample pool, and the standard deviation for each of the respective "x" and "y" brands. Kind of difficult to determine just exactly what it means with the limited data.

Kind of like the difference in accuracy and precision, although the terms get used loosely they are entirely independent of each other.

Were the loads between the two similar? velocities and bullet weights?

Fired stretches the brass to the chamber (fire formed). Some folks prefer fire formed as it fits the chamber tight. After about 3-4 shots, you will have to full length resize. Brass from different manufacturers are a little different. Hornady are soft, federal get brittle fast. Allot of good information on the web on fire forming brass etc..

My question would be, can you hit anything with the gun? lol

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Originally Posted by yobuck

My question would be, can you hit anything with the gun? lol

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That's what I figured all that matters. Yes, it does quite well, even with shelf stuff. Having some hand loads coming.

I have never had to bump the shoulder or full length size my 223 brass. I neck size only and need to trim the OAL only very occasionally. Works the brass less and it lasts longer. I do anneal occasionally, usually after a dozen loadings or so, but I have failed to see any difference in groups size after doing it. But then I'm not known for shooting consistent bughole groups

The takeaway here is to not work the brass anymore than you have to. Set your FL die to only bump what you need to get the fit you want, and use the barrel's chamber as your guide.

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Originally Posted by Texas10

I have never had to bump the shoulder or full length size my 223 brass. I neck size only and need to trim the OAL only very occasionally. Works the brass less and it lasts longer. I do anneal occasionally, usually after a dozen loadings or so, but I have failed to see any difference in groups size after doing it. But then I'm not known for shooting consistent bughole groups

The takeaway here is to not work the brass anymore than you have to. Set your FL die to only bump what you need to get the fit you want, and use the barrel's chamber as your guide.

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Thanks. MY SIL just left with the h4895, a box of 69s and a box or 60s along with a thousand CCI 400 primers. He will do a ladder test for me, so when the weather comes around, I'll give it a shot.
With no negative comments, my chamber must be fine. The only caveat is that I have no doubt the rifle shoots much better than me.

"T 10", You are a reloader after My own heart! ;-))
We are few, so We must stick together!

Fired and Unfired Brass--any correlation?

Un Fired Brass = Too Small

Brass Fired in My Chamber = Just Right :-) JMAO

I am twisting my mind around the questions (to me there are two answers) .

Probably belongs in the reloading section, maybe even shifted to to the Firing Line Reloaders Section that has a very active group of advanced reloaders (I put myself in upper middle but not advanced)

Reasonably it does not matter in that the non fired is formed to dimensions.

It gets a bit complex and you need to get a Hornady Comparator gauge set and a micrometer to follow it (and if you want to do middle to advanced reloading you need that anyway)

The comparator come in two variety's, one set of fitting to measure Bullet Ogive and the other Shoulder Setback (that gets to the heart of your questions )


1. Non fired is going to conform to sub SAMMI. I have two examples. One is and unfired Lapua 30-06 (I got a nice deal on them) and the other is an RP resized maybe 5 times
Both measure out at 2.044 at the shoulder.


2. I have a fired RP case, it measure 2.047. That is in a tight chamber in that the headspace is closer to GO and not NO GO. Once the brass is fired it does not make a lot of difference as it is now chamber formed. Longer chamber the measurements change but you set it back the same .002 (ideally)

It does matter if you shoot that round in two rifles that are different head space and or chamber dimensions. I keep separate lots for my Model of 1917 (30-06) as it by design it has a lot of head space and a lot of brass growth (combat design, not SAMMI!) - very close to field reject, they did not care, they wanted it to shoot ONE throw away piece of brass reliably no matter how muddy or carbon fouled.


So, as you can see there is .003 difference in fired, non fired re-sized and simply non fired.

Keep in mind Primer has to be seated deep not to affect readings as it changes things if even the tinniest bit is stickup up above the case (fired)


Now I will launch into my song and dance.

Re-sizing: A war rages over this subject, bench rest shooters full length resize. I don't purport to be in their class, but it also does not affect things and I by feel prefer it.
Long distance shooters some do and some don't full length, they cannot control the wind, heat waves, distortion so they are more into the art of shooting.

What works brass is not full length resizing, what works it is too much shoulder setback.

that is where the Hornady shoulder comparator comes in (I made my own so those measurements above will not apply, its all relative, my adaptor is on the shoulder but not the same place as the Hornady adapter will be)

Doesn't matter, what you are after is setting up in the sizer to do MINIUM shoulder setback. .001 is ideal, I find that its extremely difficult to achiever, and as long as it is .003 or under I am good.

If you follow the die instructions , they say, contact shell holder, then 1/8 or 1/4 more turn. That really pushes the shoulder back, that is what wears out the brass. It breaks down above the base.

If you are lucky it only cracks there and extracts fine. If not you need to get out with a case remover.

I like to use a digital micrometer as the number stick in my mind better. A tiny turn on the die when doing the shoulder setback changes things a lot.

I like the Leee rings for the die with the rubber seat as they have hex shaped and I can snug down with a wrench. the ones with the knurls on them are a pain, you are only suppose to hand tighten with all that but it does not work out (same with the upper parts, put a hex on them I say)

And longer term, necks will spit if not annealed, not because of sizing but work hardening by the powder burning


I am only shooting 30-06 and 308, for those at least in RP case the split comes about 8 to 10.

Annealing also makes sure the fit is the same for tension helping the accuracy. Not sure that is relevant for what I do but I will take what I can get.

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Originally Posted by FW Conch

"T 10", You are a reloader after My own heart! ;-))
We are few, so We must stick together!

Fired and Unfired Brass--any correlation?

Un Fired Brass = Too Small

Brass Fired in My Chamber = Just Right :-) JMAO

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Thanks, FW. I had read about this method, but it finally sunk in when my new 22-250 was growing my new Lapua brass excessively. I finally switched out the factory barrel for a match chambered 8 twist and deliberately set the headspace to minimum when installing the barrel.

I should mention here that I am shooting a bolt gun, not a semi-auto, and there is a difference in procedures between the two.

Now the shot brass measures almost exactly the same, shot to shot. I neck size only and check chamber fit as part of my cleanup procedure. If it fits, I don't need to bump the shoulder. I am using Lee dies (four die set) and am seeing great longevity in my brass life.

"Ditto" Nothing that has been said gives Me a reason not to use My rifles chamber as a case gauge. And why should I bump the shoulder .001" when the case fits the chamber at .000"? And I don't care what the measurement is to the datum line. I know it's right when the case chambers.

There's nothing I can do to curtail mas expenditures of money or chronic OCD. But not Me :-)

Different strokes for different folks

Whatever works for you

I have tried it all and most methods produce quality ammo if done correctly

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And longer term, necks will spit if not annealed, not because of sizing but work hardening by the powder burning

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This my compadres...says it all.

Wrong Robinhood and RC20. Burning powder doesn't harden the brass, working it does. Running it in the die to squeeze it down and firing it are how it is hardened. Wouldn't matter how it is stretched and squeezed the movement is what hardens it.

Anybody ever put Tempi-lac on the neck of a live round and see if it gets to annealing temperature during firing? That blow torch of hot gas must get the brass pretty hot, especially with powders known for building heat.

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Originally Posted by earl39

Wrong Robinhood and RC20. Burning powder doesn't harden the brass, working it does. Running it in the die to squeeze it down and firing it are how it is hardened. Wouldn't matter how it is stretched and squeezed the movement is what hardens it.

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I stand corrected, it is indeed the working and stretching going on. Trying to say a lot and got myself turned around.

And no have not tried Templec in that application. Obviously it does not correct the brass with the created heat ergo need to anneal. Speculation as to why, heat sink in contact with the chamber may preclude that.

As too much heat just softens it permanently the flip could also happen but does not.

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Originally Posted by earl39

Wrong Robinhood and RC20. Burning powder doesn't harden the brass, working it does. Running it in the die to squeeze it down and firing it are how it is hardened. Wouldn't matter how it is stretched and squeezed the movement is what hardens it.

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I was not agreeing Mr eatl39. I was making a point.

I think we have defined thread drift.

Well not too far though I think its pretty well answered.