Case head expansion & ready to retire

[badmatrix]

I gauge the retirement of any given piece of brass by the primer pocket condition. I use a ballistic tools primer pocket gauge: go-nogo.

Case head expansion: is this something that is gradual under normal wear and tear until the case won’t chamber or fails the gauge check, then you retire?

.NOT CONCERNED RIGHT NOW ABOUT CASE SEPARATION, BUT EXPANSION….

 

[jcj54]

It depends on the rifle. In a bolt action you can reload a case more times than in a semi auto. The concern is not expansion ahead of the extractor groove it is thinning of the case in this area. Every loading manual I have explains hoe you check for this with a bent paperclip inserted in the case. The worry is case head separation. I discard my .308 and .30-06 cases after 6 loadings. I lost count once and had 3 case head separations which made me more meticulous on record keeping.
Sometimes you will see a shiny ring around the case a bit forward of the extractor groove which is a warning the brass is dangerously thin there.

 

[badmatrix]

Thanks… i’m not concerned about Case head separation. Only the case head expansion that makes the cartridge a little more difficult to chamber. I can’t post a picture here to show the forum and what I’m talking about.

 

[jcj54]

If you are having such issues after full length sizing you probably need a small base full length sizing die.

 

[HiBC]

Case head expansion is an old school (stone knives and bear skins)way to monitor excessive pressure.

In many rifle designs (Such as 1903 and Win M-70) the cone breech leaves the case head unsupported by chamber. The brass is designed for this. If the case head is expanding,its time to pay attention.
But these "pressure sign" indicators are something like tea leaves,bat wings and fire smoke paths. Not to be ignored,but not the last word.

Case head expansion is a pretty credible "sign" .

The case head area is concentric with he primer pocket. Kind of like a donut and donut hole. Generally if the donut hole gets bigger so does the donut.
The loosening of primer pockets would generally suggest an accompanying case head expansion. Maybe.
But I don't suggest jumping to conclusions.
It might be interesting to get a series of pin gauges increasing in size by .0001 per pin to gauge the pockets versus the case heads.
With enough samples and enough data and enough "isolation of variables" you might be able to observe a trend.

Sounds tedious. Not necessarily fun. IMO, as a general trend, if we recognize the "margin of safety" our component suppliers recommend ,work up our loads,etc.... I'll say I started loading in the 1960's buying Hodgdon powder dispensed into my bleach bottle or the brown paper bag Louis P B would provide. $ 1.60 a lb.No Youtube. No forums. Some had "Powley P-max" .... but not me .Q+A columns by PO Ackley and Elmer. Warren Page articles. And the trusty load manual.
And,of course, being young,I did plenty of "Dumb" . Intial load development for my 257 Roberts AI found me at the range next to a gentleman with an Oehler 33 Chronograph. I asked him if he'd clock a few. He was happy to.
He got real excited , started dancing and waving his hat. "What are you shooting? "
"IMR4350 behind a Sierra 100 gr boat tail. "

"Well,you are getting 3400 fps with less than 10 fps spread!."

I pondered on that a bit. I was right there with the hotter 25-06 and 257 Weatherby loads in the book. There ain't any magic or free lunch. I was just a few granules over book MAX. That old Mexican Mauser ..... was old.

I considered the bolt going through my cheekbone. 3400 fps? Hmmmm .

Probably ought to back off a bit.

Pushing the limit,I surmised,was not only approaching the edge of the cliff,it was dancing at the edge of the cliff. After a couple of beers.
Anyway,well over 50 years worth of reloading ,finding my own path and not one time did anything get too exciting. No kabooms.

Stretch rings and case separations are a different "Symptom " than "head expansion" . Head expansion,IMO, tells me pressure is (maybe) high enough
to cold flow brass. Stretch rings tell me "There is enough head clearance to shorten case life". That can happen at safe pressures . There are case measuring and resizing adjustments we can try to control head clearance.

It hurts to find "that load" that results in your lot of 223 brass being scrap to loose pockets. Generally,it takes a bad screw up to Kaboom with a .223/5.56.
Like pistol powder.
But you can easily loosen primer pockets . A few extra fps can mean scrapping all that expensive,hard to come by brass you laboriously prepped.
Dang it!
Good reason to NOT push the limit. Better to add a click or two elevation at the sights.

 

[gwpercle]

I load them untill a crack develops or lost in the weeds !

No measuring required or gauge is required .

Us old guys who learned to reload in the 1960's ... We only had 12 inch ruler , 36 inch yardstick and 20 foot tape measure to measure with and I never have owned a Primer Pocket Gauge ... if the primer don't fall out ...what else you need to know !
Gary

 

[Unclenick]

While case head expansion has proven useless at reporting the value of the peak pressure reached by a load, it is still a perfectly valid indicator of when the individual case is having problems enduring the pressure it is being subjected to. When you have enough case head expansion that the primer pockets are getting loose, you are also right to be concerned you are approaching some other problems. These would include primers falling out of the cartridge in your magazine and gas leaks pockmarking your bolt face. It is probably an indicator the bent paperclip test should be run on the case, though it doesn't necessarily mean you will find a problem when you do. There used to be a tool made for tightening primer pockets back up when someone found an otherwise good case that had too much primer pocket spread, but it has been discontinued, unfortunately.

 

[badmatrix]

Case head expansion is an old school (stone knives and bear skins)way to monitor excessive pressure.

In many rifle designs (Such as 1903 and Win M-70) the cone breech leaves the case head unsupported by chamber. The brass is designed for this. If the case head is expanding,its time to pay attention.
But these "pressure sign" indicators are something like tea leaves,bat wings and fire smoke paths. Not to be ignored,but not the last word.

Case head expansion is a pretty credible "sign" .

The case head area is concentric with he primer pocket. Kind of like a donut and donut hole. Generally if the donut hole gets bigger so does the donut.
The loosening of primer pockets would generally suggest an accompanying case head expansion. Maybe.
But I don't suggest jumping to conclusions.
It might be interesting to get a series of pin gauges increasing in size by .0001 per pin to gauge the pockets versus the case heads.
With enough samples and enough data and enough "isolation of variables" you might be able to observe a trend.

Sounds tedious. Not necessarily fun. IMO, as a general trend, if we recognize the "margin of safety" our component suppliers recommend ,work up our loads,etc.... I'll say I started loading in the 1960's buying Hodgdon powder dispensed into my bleach bottle or the brown paper bag Louis P B would provide. $ 1.60 a lb.No Youtube. No forums. Some had "Powley P-max" .... but not me .Q+A columns by PO Ackley and Elmer. Warren Page articles. And the trusty load manual.
And,of course, being young,I did plenty of "Dumb" . Intial load development for my 257 Roberts AI found me at the range next to a gentleman with an Oehler 33 Chronograph. I asked him if he'd clock a few. He was happy to.
He got real excited , started dancing and waving his hat. "What are you shooting? "
"IMR4350 behind a Sierra 100 gr boat tail. "

"Well,you are getting 3400 fps with less than 10 fps spread!."

I pondered on that a bit. I was right there with the hotter 25-06 and 257 Weatherby loads in the book. There ain't any magic or free lunch. I was just a few granules over book MAX. That old Mexican Mauser ..... was old.

I considered the bolt going through my cheekbone. 3400 fps? Hmmmm .

Probably ought to back off a bit.

Pushing the limit,I surmised,was not only approaching the edge of the cliff,it was dancing at the edge of the cliff. After a couple of beers.
Anyway,well over 50 years worth of reloading ,finding my own path and not one time did anything get too exciting. No kabooms.

Stretch rings and case separations are a different "Symptom " than "head expansion" . Head expansion,IMO, tells me pressure is (maybe) high enough
to cold flow brass. Stretch rings tell me "There is enough head clearance to shorten case life". That can happen at safe pressures . There are case measuring and resizing adjustments we can try to control head clearance.

It hurts to find "that load" that results in your lot of 223 brass being scrap to loose pockets. Generally,it takes a bad screw up to Kaboom with a .223/5.56.
Like pistol powder.
But you can easily loosen primer pockets . A few extra fps can mean scrapping all that expensive,hard to come by brass you laboriously prepped.
Dang it!
Good reason to NOT push the limit. Better to add a click or two elevation at the sights.

Thank you. I never load near max load. I wish i could post an image here.

 

[Black wallnut]

Jcj54, if you are scrapping cases after 6 reloads you might take a look at how much you are working the brass and how much excessive headspace your firearms have. Check length after each use, trim when too long. I have brass that has been trimmed at least twice with no signs of head separation. If you have a loose chamber and tight dies and FL each time maybe after six you might have the beginning of a problem.

But it's your rifle and brass and you do you. I only object because although it works for you, it is not very good advice for others.

 

[LAH]

NO WAY TO POST A PICTURE HERE….NOT CONCERNED RIGHT NOW ABOUT CASE SEPAEATION, BUT EXPANSION

https://thefiringline.com/forums/showthread.php?t=292842

 

[badmatrix]

Thank you big thanks!

 

[badmatrix]

Here is what i am talking about. Case expansion enough to make chambering a little harder. This was one out of 20. But sometimes a few more do this.

 

[stagpanther]

When you put the case in the guage--does the head actually wedge to the walls of the guage? The reason I ask is that it might also be possible your headspacing off the shoulder datum of the chamber was too long when fired and the case shoulder base expanded forward as a result. This is actually rather common with cartridges like the creedmoor when used in a semi-auto and might require knocking the shoulder back when resizing--but not so much so that the case expands too much resulting in overworking the brass. These case guages are handy approximations--but they don't give you an exact replica of your rifle's chamber dimensions.

 

[Jim Watson]

There used to be a tool made for tightening primer pockets back up when someone found an otherwise good case that had too much primer pocket spread,

The first I ever heard of Loctite, an intrepid loader was using it to glue primers into expanded pockets. I know a guy who still does it.

 

[badmatrix]

When you put the case in the guage--does the head actually wedge to the walls of the guage? The reason I ask is that it might also be possible your headspacing off the shoulder datum of the chamber was too long when fired and the case shoulder base expanded forward as a result. This is actually rather common with cartridges like the creedmoor when used in a semi-auto and might require knocking the shoulder back when resizing--but not so much so that the case expands too much resulting in overworking the brass. These case guages are handy approximations--but they don't give you an exact replica of your rifle's chamber dimensions.

To be clear, this happens to a small small fraction of any given batch. Brass is fire formed for bolt action rifles. My brass is annealed, resized, cleaned, trimmed, chamfered-etc, primed and charged according to all respective Hornady load and bullet data. When resized, i used a comparator to resize to a median SAAMI value headspace of I think 1.547” for this batch of 168 cartridges.

 

[Unclenick]

Badmatrix,

Apply some Magic Marker to the sides of one of the problem cases, push it into the gauge, and pull it out. See if the MM ink is scuffed off the sides. If so, the case is not returning to SAAMI dimensions, may have become too springy for a standard sizing die, and may require a small base die. If not, you want to use a comparator to look at the shoulder datum position with respect to the head as compared to cases that fit in the gauge. If you don't own one of the nearly ubiquitous Hornady tools for this, you can improvise, as illustrated below with spacer sized for a .308 case shoulder (the Lowe's spacers are a bit oversize), which will be the same for 6.5 CM.

 

[totaldla]

I gauge the retirement of any given piece of brass by the primer pocket condition. I use a ballistic tools primer pocket gauge: go-nogo.

Case head expansion: is this something that is gradual under normal wear and tear until the case won’t chamber or fails the gauge check, then you retire?

.NOT CONCERNED RIGHT NOW ABOUT CASE SEPARATION, BUT EXPANSION….

I used to throw away cases when the primer pocket felt loose when priming. Then I started reloading 223 in bulk, and I was loathe to throw away brass I'd put so much prep work into without good cause. So I stopped chucking cases based on hiw they prime. A scazillion rounds later I looked at my bolt face and didn't see any pitting or erosion. So now I'm thinking that judging 223 brass by priming force is a waste.

I used to do the same thing with Remington 270W brass as the pockets seemed to loosen significantly after 1 reload cycle. I'm wondering if I didn't throw away perfectly good brass because I had a faulty metric.

I now am careful with 223 to not get carried away bumping the shoulder, and I keep my loads moderate. My blasting brass is at 5 cycles so far without cracks and I'm not going to anneal - I'll eventually find out first-hand how long the brass will really last.

 

[badmatrix]

I used to throw away cases when the primer pocket felt loose when priming. Then I started reloading 223 in bulk, and I was loathe to throw away brass I'd put so much prep work into without good cause. So I stopped chucking cases based on hiw they prime. A scazillion rounds later I looked at my bolt face and didn't see any pitting or erosion. So now I'm thinking that judging 223 brass by priming force is a waste.

I used to do the same thing with Remington 270W brass as the pockets seemed to loosen significantly after 1 reload cycle. I'm wondering if I didn't throw away perfectly good brass because I had a faulty metric.

I now am careful with 223 to not get carried away bumping the shoulder, and I keep my loads moderate. My blasting brass is at 5 cycles so far without cracks and I'm not going to anneal - I'll eventually find out first-hand how long the brass will really last.

I started using the ballistic tools line of primer pocket gauges and those for neck tension.

https://ballistictools.com/store/small-and-large-primer-pocket-gauges

The case gauges are what bring me here to post about. I have given up for now on bumping shoulders because it caused me to resize waaaay above SAAMI max for headspace and I was getting misfires and light primer strikes.

Like i said, i picked a HS measurement in the median range of the SAAMI specs. and will head to the range Thursday to test my reloads doing it this way.

The head space expansion is just a distraction i encountered and wanted to see what you guys had seen over space and time.

 

[Unclenick]

The case gauges are what bring me here to post about. I have given up for now on bumping shoulders because it caused me to resize waaaay above SAAMI max for headspace and I was getting misfires and light primer strikes.

That is worrisome because it suggests your chamber has headspace "waaaay" above SAAMI maximum. Also, you say it is causing misfires. That sounds backward. Bump-sized cases should fit the chamber better so the shoulder stops the case going forward and holds the head back against the bolt face, thereby giving you better resistance for the firing pin to strike the primer against. Taken altogether, this says something is wrong. I think you need to get a chamber cast made. Between cases getting too fat and way too long, I am starting to get the uneasy feeling that someone ran the wrong chambering reamer into your barrel or ran the right one in way too far.

 

[badmatrix]

That is worrisome because it suggests your chamber has headspace "waaaay" above SAAMI maximum. Also, you say it is causing misfires. That sounds backward. Bump-sized cases should fit the chamber better so the shoulder stops the case going forward and holds the head back against the bolt face, thereby giving you better resistance for the firing pin to strike the primer against. Taken altogether, this says something is wrong. I think you need to get a chamber cast made. Between cases getting too fat and way too long, I am starting to get the uneasy feeling that someone ran the wrong chambering reamer into your barrel or ran the right one in way too far.

No. Sorry. All that was before this 168 batch of brass. I am not very clear…and..no…it isn’t the rifle….it has been back to Bergara for another issue. I cannot talk about bumping in this discussion cuz we will go off into the weeds…..