Another headspace question.

[Timon]

A few years back I had a custom rifle built with a Pierce action. Pierce cut the chamber and built the rifle. It is chambered in .223 Remington. I started shooting the rifle using Lapua brass and fired a few hundred so that I would have some once fired brass to work with. I then became ill and have not been able to load or shoot for about a year and a half. I decided to start reloading the Lapua brass a bit and might even try to make a range trip.
Using a comparator I measured the “headspace”on the fired .223 case. Then I measured the “headspace” on a virgin case. I found that the two measurements were exactly the same, there did not appear to be any shoulder expansion. I did find a few thou of OD expansion on the fired case near its base.
My question is this, is it normal to get no shoulder expansion on a once fired piece of brass?
I did check a number of other fired cases and they were the same.
I did not load these rounds heavy, but they were not light either for a .223.
Just looking for some input before I start loading the rounds again.
Any thoughts folks?

 

[rwj]

First, it’s great to hear that you’re well enough to start shooting again ! It may take several firings for all the case surfaces to expand to the extent they contact the chamber.

 

[Timon]

First, it’s great to hear that you’re well enough to start shooting again ! It may take several firings for all the case surfaces to expand to the extent they contact the chamber.

Would you then full length size, but leave the shoulder as is?

 

[Shooter13]

Do they still chamber in the gun with no signs of force to close the bolt?

 

[whatsupdoc]

You have a tight chamber, if the new Lapua brass chambered without issue you are just fine.
Your brass will last for a very long time.
I headspace reamage setups using new brass as the gauge and after firing I bump the shoulder back
by .002.

 

[Timon]

Do they still chamber in the gun with no signs of force to close the bolt?

No issue at all

 

[Timon]

You have a tight chamber, if the new Lapua brass chambered without issue you are just fine.
Your brass will last for a very long time.
I headspace reamage setups using new brass as the gauge and after firing I bump the shoulder back
by .002.

Would you bump it one or two thou still, or leave it as is?

 

[M-61]

Do they still chamber in the gun with no signs of force to close the bolt?

That is what will answer your question #7
If they do, then leave them alone.

 

[CharlieNC]

Partially insert a primer, chamber it, close the bolt to finish seating the primer. Remove and measure the headspace; this dimension represents "zero headspace" from which you want 0.002 nominal bump.

 

[rwj]

Would you then full length size, but leave the shoulder as is?

Sizing the body and neck is fine, but I would not bump the shoulder as others have replied…

 

[whatsupdoc]

Would you bump it one or two thou still, or leave it as is?

After I fire new brass I bump the shoulder back .002 every time it gets fired.

 

[WayneShaw]

You don't need gauges to determine how much to resize. Take the striker out of the bolt, back your sizing die out a bit, then size a brass, wipe it off and try it in your chamber by closing the bolt, with feel. Did the bolt drop, did it have resistance? Adjust your sizing die accordingly. When you feel a SLIGHT feel closing the bolt, you are where you want to be.

 

[243winxb]

I did find a few thou of OD expansion on the fired case near its base.

The case may grow, shoulder expansion, as the case body is sized.

My question is this, is it normal to get no shoulder expansion on a once fired piece of brass?

Not common. Can happen with light to midrange loads. . As the case body expands on firing, the shoulder may pull back. The trim length will also become shorter.

FL sizing moves them forward again.

 

[Timon]

The case may grow, shoulder expansion, as the case body is sized.

Not common. Can happen with light to midrange loads. . As the case body expands on firing, the shoulder may pull back. The trim length will also become shorter.

FL sizing moves them forward again.

Let me ask this though. If, in this case, the shoulder pulls back when fired, why is it the exact same length as the unfired brass?

 

[divingin]

Brass under pressure becomes somewhat fluid.

In general, the cases will expand to fill the chamber (except where brass thickness deters that - at the base); and the case will get marginally shorter. Resizing will squeeze the diameter at any point down, and lengthen the case. Pushing the shoulder back causes the neck to grow longer (as the brass has to go somewhere.)

Those are generalizations, as stated, though, and can change for specific circumstances. If, say, the case expands to the chamber walls (radial expansion), but does not get driven back against the breech face, you could expect that the length would not change, or it would shrink. Conversely, if it does get driven back, the base to shoulder length will grow, and the overall case length may or may not change depending on how the brass flows. Easier, IMO, to measure and see what's happening and deal with that, rather than spend a lot of time trying to predict what'll happen and figure out why it didn't.

 

[243winxb]

Let me ask this though. If, in this case, the shoulder pulls back when fired, why is it the exact same length as the unfired brass?

As the case body expands on firing, the shoulder may pull back

Just an example of what is possible.

 

[BDman]

Several brands of .223 brass and most .556 brass will not expand to fit the chamber without near maximum loads. I set a FL die to not bump the shoulder and check them after firing. I seldom have to bump them.