Monitoring for excess pressure-case head expansion best?

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Re: Monitoring for excess pressure-case head expansion best?

Post by Oldbloke » 09 Sep 2021, 6:32 pm

DD is just starting out reloading. Looking to reload to hunt and save a few $.

Providing they are boxer type they will be fine.
Deprime
Clean if needed
Anneal if so inclined.
FL resize
Trim and deburr if required

Job done.
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Re: Monitoring for excess pressure-case head expansion best?

Post by SCJ429 » 09 Sep 2021, 6:36 pm

Part of the fun of reloading is to find out how fast you can send your projectile. Often by pushing on you can find a faster node. I have been known to see how far a case can be pushed. It is harder on brass and barrel life.

The primers can be the weak link and blowing primers is hard on your bolt face so best avoided but flattened and mushroomed primers are not the best signs of pressure. As said previously, your firing pin hole may be too large and this causes the problem which you can fix with a bushing. You could also use a primer with a harder cup or if it is an option to you, use small primer brass.

I notice case head expansion when sizing my brass. More force is required. I seldom see the beginnings of case head separation when using high pressure. If you want to push it, use a reamer that gives you a tight chamber and don't push your brass around a lot when resizing.
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Re: Monitoring for excess pressure-case head expansion best?

Post by northdude » 09 Sep 2021, 8:07 pm

bladeracer wrote:
northdude wrote:see if you can feel how many flash holes it has the mil stuff over here has 2


Surely not the modern stuff?

seems to pop up from time to time here don't know where it comes from or how old. I'm in nz not aussie
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Re: Monitoring for excess pressure-case head expansion best?

Post by bladeracer » 09 Sep 2021, 8:16 pm

northdude wrote:
bladeracer wrote:
northdude wrote:see if you can feel how many flash holes it has the mil stuff over here has 2


Surely not the modern stuff?

seems to pop up from time to time here don't know where it comes from or how old. I'm in nz not aussie


I don't even think the Chinese still make Berdan ammo.
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Re: Monitoring for excess pressure-case head expansion best?

Post by Downunder » 10 Sep 2021, 8:18 am

How far you go down the rabbit hole depends on why you’re handloading X your personality.
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Re: Monitoring for excess pressure-case head expansion best?

Post by disco stu » 10 Sep 2021, 9:19 am

Downunder wrote:How far you go down the rabbit hole depends on why you’re handloading X your personality.


My personality means I need to avoid rabbit holes at all costs :D Perfectionist tendencies and inquisitive mindset combined with science background makes me want to try all possibilities, which often sees me spending months testing and trying a heap of different things, before realising that what I got on day 2 was more than good enough for my intended purposes. I've at least been around long enough to know myself well enough in this regard!

Should have seen me building a bow press. Spent over a month on it coming up with crazy ideas and missing different bits that just ended up to complicated. I wound it right back to something simple with minor tweaks that works perfectly. I even modified it further by making it even more simple, while slapping myself in the face

My goal for this at least is a load that isn't stupid slow and is accurate for hunting. It appears that the difference between fast and slow in the loads I've looked at is only a few hundred fps, which isn't going to matter much at the ranges I hunt at-I'm not at the stage of taking 300m shots yet at animals, that's if I even had anywhere I could see them at that range. So it's really under 200m max.

SCJ429 wrote:.....

I notice case head expansion when sizing my brass. More force is required. I seldom see the beginnings of case head separation when using high pressure. If you want to push it, use a reamer that gives you a tight chamber and don't push your brass around a lot when resizing.


I can probably have a play looking at faster loads etc later on when I'm more experienced and have a better idea of what I'm looking at, if I'm so inclined. Reaming chambers is getting well outside the direction I want to head in though. Got to stay focused on my goal, which is filling the freezer
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Re: Monitoring for excess pressure-case head expansion best?

Post by disco stu » 10 Sep 2021, 9:28 am

I should add, my only reason for asking this question was in regards to safety, not because I have the intention of pushing things towards max etc. The manuals all push that you have to monitor every load for over pressure, even the lightest ones, and I just worried that my inexperience might mean I miss signs. Something quantifiable like a measurement takes my (possibly incorrect) interpretation out of it I was thinking
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Re: Monitoring for excess pressure-case head expansion best?

Post by SCJ429 » 10 Sep 2021, 12:29 pm

The most obvious signs are a bolt that is harder to open and the shiney mark on the head stamp of your case where the brass is trying to migrate into the extractor. Keep aware and you won't miss these signs.
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Re: Monitoring for excess pressure-case head expansion best?

Post by disco stu » 10 Sep 2021, 1:12 pm

SCJ429 wrote:The most obvious signs are a bolt that is harder to open and the shiney mark on the head stamp of your case where the brass is trying to migrate into the extractor. Keep aware and you won't miss these signs.


Awesome, thanks.
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Re: Monitoring for excess pressure-case head expansion best?

Post by northdude » 10 Sep 2021, 2:45 pm

It can also be dangerous under loading as well cant remember exactly why. I tend to load somewhere around the middle of min and max book loads.
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Re: Monitoring for excess pressure-case head expansion best?

Post by bladeracer » 10 Sep 2021, 4:02 pm

northdude wrote:It can also be dangerous under loading as well cant remember exactly why. I tend to load somewhere around the middle of min and max book loads.


Called Secondary Explosion Effect.
Can happen with very light charges of slow powders in very large cases, rarely any problem with fast powders.

Very few load data list minimum loads, they usually list a starting load and a maximum load. You can go lower than the starting load. It's more a point to start load development knowing you're well short of high pressures.
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Re: Monitoring for excess pressure-case head expansion best?

Post by disco stu » 10 Sep 2021, 5:11 pm

I was reading that is not an issue in fast powders, but where is the line between slow and fast in this regard?

I gather the safe method is dropping 10% from max load or full case for minimum load, is that correct?
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Re: Monitoring for excess pressure-case head expansion best?

Post by bladeracer » 10 Sep 2021, 5:19 pm

disco stu wrote:I was reading that is not an issue in fast powders, but where is the line between slow and fast in this regard?

I gather the safe method is dropping 10% from max load or full case for minimum load, is that correct?


Generally you'll find the powder manufacturers won't even list faster powders in the large cartridges as they're not very efficient in them, so they're likely to all be fairly slow burning. There are burn rate charts online to judge whether your powder is faster or slower. Pistol and shotgun powders are the fastest.

Some load data only list a maximum charge, and tell you to start below that, usually 10%.

I've never seen data based on case fill.
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Re: Monitoring for excess pressure-case head expansion best?

Post by disco stu » 10 Sep 2021, 9:16 pm

Cheers. I read with interest in one book about turkey loads, summed up exactly what I was hoping to eventually do in the 308. Used small loads of fast powder with light projectiles. It just left me uncomfortable even though he said that it's not an issue with fast powders
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Re: Monitoring for excess pressure-case head expansion best?

Post by bladeracer » 10 Sep 2021, 9:50 pm

disco stu wrote:Cheers. I read with interest in one book about turkey loads, summed up exactly what I was hoping to eventually do in the 308. Used small loads of fast powder with light projectiles. It just left me uncomfortable even though he said that it's not an issue with fast powders


Trailboss is the ideal for reduced loads. It's a very fast powder but is about one-third the density of most powders, so very light loads fill the case fully.
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Re: Monitoring for excess pressure-case head expansion best?

Post by Oldbloke » 10 Sep 2021, 9:58 pm

This has been around a long time but is a good explanation.

Explosive detonation.jpeg
Explosive detonation.jpeg (38.52 KiB) Viewed 4274 times


And there is this from the ADI manual.

Reduced loads 75% of Case capacity.JPG
Reduced loads 75% of Case capacity.JPG (39.94 KiB) Viewed 4274 times


And this.

Reduced loads 60% max 2206H.JPG
Reduced loads 60% max 2206H.JPG (72.59 KiB) Viewed 4274 times
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Re: Monitoring for excess pressure-case head expansion best?

Post by disco stu » 10 Sep 2021, 11:31 pm

Thanks OB. 75% leaves a bit more leeway.

Yeah BR, trail boss is what I have in mind, but I've heard it's not available in Australia at the moment, or something to that effect. I was intending to use 2206h on the advice of Old Bloke so I can reduce loads to 60%.
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Re: Monitoring for excess pressure-case head expansion best?

Post by bladeracer » 11 Sep 2021, 12:51 am

disco stu wrote:Thanks OB. 75% leaves a bit more leeway.

Yeah BR, trail boss is what I have in mind, but I've heard it's not available in Australia at the moment, or something to that effect. I was intending to use 2206h on the advice of Old Bloke so I can reduce loads to 60%.


Yep, unfortunately ADI has put production of all pistol/shotgun powders and some less-popular rifle powders on hold for a couple years.
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Re: Monitoring for excess pressure-case head expansion best?

Post by Downunder » 11 Sep 2021, 4:08 am

disco stu wrote:
Downunder wrote:How far you go down the rabbit hole depends on why you’re handloading X your personality.


My personality means I need to avoid rabbit holes at all costs :D Perfectionist tendencies and inquisitive mindset combined with science background makes me want to try all possibilities, which often sees me spending months testing and trying a heap of different things, before realising that what I got on day 2 was more than good enough for my intended purposes. I've at least been around long enough to know myself well enough in this regard!

Should have seen me building a bow press. Spent over a month on it coming up with crazy ideas and missing different bits that just ended up to complicated. I wound it right back to something simple with minor tweaks that works perfectly. I even modified it further by making it even more simple, while slapping myself in the face

My goal for this at least is a load that isn't stupid slow and is accurate for hunting. It appears that the difference between fast and slow in the loads I've looked at is only a few hundred fps, which isn't going to matter much at the ranges I hunt at-I'm not at the stage of taking 300m shots yet at animals, that's if I even had anywhere I could see them at that range. So it's really under 200m max.


My 2c....
Basic reloading set up I’ll assume you’ll have a set of vernier callipers good to .000”, whilst not the highest precision tool it will give you an idea of any growth. Measure a factory unfired round, compare it to SAAMI and file the info, then down the track when you feel the need to measure a resized xx fired case and compare you can.

To be honest its very rare I measure the head or even see any expansion or excessive brass flow from the head in my loading and I load beyond manuals for 2 cartridges with brass life still well in the teens and even into the 2’s.
Exclusively it’s primer pockets with some shoulder and neck Issues that eventually takes brass out of service for me.

Unless your brass cycle is hyper quick ie you’re hunting for woolies or a tribe or have only 3 pc’s of brass then following the data of respected loading manuals I doubt very much that you’ll see any issues at the head.
My comment assumes you’re using quality components in a modern maintained quality firearm.
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Re: Monitoring for excess pressure-case head expansion best?

Post by disco stu » 11 Sep 2021, 8:43 am

bladeracer wrote:
Yep, unfortunately ADI has put production of all pistol/shotgun powders and some less-popular rifle powders on hold for a couple years.
AR2206H is incredibly versatile, great in virtually anything.


That's a shame. Wonder if they're blaming covid :D
Sounds like the 2206h is a good option, cheers. I might end up loading for friends so would like something versatile

Downunder wrote:[

My 2c....
Basic reloading set up I’ll assume you’ll have a set of vernier callipers good to .000”, whilst not the highest precision tool it will give you an idea of any growth. Measure a factory unfired round, compare it to SAAMI and file the info, then down the track when you feel the need to measure a resized xx fired case and compare you can.

To be honest its very rare I measure the head or even see any expansion or excessive brass flow from the head in my loading and I load beyond manuals for 2 cartridges with brass life still well in the teens and even into the 2’s.
Exclusively it’s primer pockets with some shoulder and neck Issues that eventually takes brass out of service for me.

Unless your brass cycle is hyper quick ie you’re hunting for woolies or a tribe or have only 3 pc’s of brass then following the data of respected loading manuals I doubt very much that you’ll see any issues at the head.
My comment assumes you’re using quality components in a modern maintained quality firearm.


Thanks. Yes, got vernier calipers that are good to 0.0005" or 0.01mm. I figured it wouldn't hurt to measure also, but I've now got a really good idea what I'm looking for in other signs thanks to all of the advice given here.

Brass life is also much greater than I first thought. Someone told me ages ago it was only good for about 5 reloads or less, which is obviously not the case
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Re: Monitoring for excess pressure-case head expansion best?

Post by Downunder » 11 Sep 2021, 9:15 am

Downunder wrote:[

My 2c....
Basic reloading set up I’ll assume you’ll have a set of vernier callipers good to .000”, whilst not the highest precision tool it will give you an idea of any growth. Measure a factory unfired round, compare it to SAAMI and file the info, then down the track when you feel the need to measure a resized xx fired case and compare you can.

To be honest its very rare I measure the head or even see any expansion or excessive brass flow from the head in my loading and I load beyond manuals for 2 cartridges with brass life still well in the teens and even into the 2’s.
Exclusively it’s primer pockets with some shoulder and neck Issues that eventually takes brass out of service for me.

Unless your brass cycle is hyper quick ie you’re hunting for woolies or a tribe or have only 3 pc’s of brass then following the data of respected loading manuals I doubt very much that you’ll see any issues at the head.
My comment assumes you’re using quality components in a modern maintained quality firearm.


Thanks. Yes, got vernier calipers that are good to 0.0005" or 0.01mm. I figured it wouldn't hurt to measure also, but I've now got a really good idea what I'm looking for in other signs thanks to all of the advice given here.

Brass life is also much greater than I first thought. Someone told me ages ago it was only good for about 5 reloads or less, which is obviously not the case[/quote]

Verniers that to the 4th place are only very marginally more accurate the those that go to the third place as they only display in .0005 increments and not .0001.

A lot of factors go into brass life, but assuming it’s good quality brass overworking hardened brass is the largest premature failure reason I’ve found.
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Re: Monitoring for excess pressure-case head expansion best?

Post by straightshooter » 12 Sep 2021, 8:41 am

BladeMicPressure.jpg
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For those that are interested, the only reliable way to evaluate excessive pressure in a 'high pressure' cartridge is to eliminate as many measurement variables as possible.
That is done by using a blade micrometer scaled in 0.0001 inch graduations or better still 0.001mm and measure in the extractor groove. (see picture)
The method is to make 3 measurements of diameter around the groove at 1/3rd of a rotation each and calculate the average before firing. Then do the same after firing. If there is as much as 0.0005 inch increase in average diameter then the pressure of the load recipe being employed is excessive for the case head hardness and temper in the brass being used.
Ideally for reliability this measurement procedure would be repeated over a number of samples for a reliable evaluation.
Also this method is only really useful in cartridges that operate in the 50 000 CUP or 60 000 PSI range which is approaching the ultimate tensile strength of brass.
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Re: Monitoring for excess pressure-case head expansion best?

Post by bladeracer » 12 Sep 2021, 8:45 am

straightshooter wrote:
BladeMicPressure.jpg
For those that are interested, the only reliable way to evaluate excessive pressure in a 'high pressure' cartridge is to eliminate as many measurement variables as possible.
That is done by using a blade micrometer scaled in 0.0001 inch graduations or better still 0.001mm and measure in the extractor groove. (see picture)
The method is to make 3 measurements of diameter around the groove at 1/3rd of a rotation each and calculate the average before firing. Then do the same after firing. If there is as much as 0.0005 inch increase in average diameter then the pressure of the load recipe being employed is excessive for the case head hardness and temper in the brass being used.
Ideally for reliability this measurement procedure would be repeated over a number of samples for a reliable evaluation.
Also this method is only really useful in cartridges that operate in the 50 000 CUP or 60 000 PSI range which is approaching the ultimate tensile strength of brass.


I don't see any value in measuring in the extractor groove as the brass is essentially solid at that point.
I measure just ahead of the groove.
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Re: Monitoring for excess pressure-case head expansion best?

Post by straightshooter » 12 Sep 2021, 8:55 am

That is precisely the point of measuring where the brass is solid.
The purpose is to know whether the ultimate tensile strength of the hardest part of the brass case is being exceeded and not whether you are measuring the deformation of a thin section of softer brass that is intended to deform.
Or a tapered section of brass that can't be easily reliably measured.
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Re: Monitoring for excess pressure-case head expansion best?

Post by bladeracer » 12 Sep 2021, 9:04 am

straightshooter wrote:That is precisely the point of measuring where the brass is solid.
The purpose is to know whether the ultimate tensile strength of the hardest part of the brass case is being exceeded and not whether you are measuring the deformation of a thin section of softer brass that is intended to deform.
Or a tapered section of brass that can't be easily reliably measured.


I understand that, but it requires immense pressure to expand the solid brass. By monitoring any expansion up higher, closer to the walls I would avoid ever getting near those sorts of pressures. Basically, I think the pressures that lead to expansion within the groove are far above where any of us should be shooting.
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Re: Monitoring for excess pressure-case head expansion best?

Post by SCJ429 » 13 Sep 2021, 8:15 am

You can tell if the area around the extractor groove expands as your shell holder gets a bit tighter and your primer pockets get loose.
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Re: Monitoring for excess pressure-case head expansion best?

Post by animalpest » 13 Sep 2021, 9:47 am

I measure ahead of the extractor groove. Using a standard micrometer I file the rim so that when I measure the solid web the rim doesn't get in the way. This way you have a single place to measure on each cartridge case.

Pressure signs are excessive when there is more than 2 thou expansion on a once fired case.
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Re: Monitoring for excess pressure-case head expansion best?

Post by straightshooter » 19 Sep 2021, 8:27 am

bladeracer wrote:
straightshooter wrote:That is precisely the point of measuring where the brass is solid.
The purpose is to know whether the ultimate tensile strength of the hardest part of the brass case is being exceeded and not whether you are measuring the deformation of a thin section of softer brass that is intended to deform.
Or a tapered section of brass that can't be easily reliably measured.


I understand that, but it requires immense pressure to expand the solid brass. By monitoring any expansion up higher, closer to the walls I would avoid ever getting near those sorts of pressures. Basically, I think the pressures that lead to expansion within the groove are far above where any of us should be shooting.

I think you still don't get it and I suspect you may possibly have lost sight of a characteristic of gas under pressure being that it exerts that unit pressure equally over the internal surface of it's containment.
Firstly 'immense pressure' is what makes modern cartridges and modern powders deliver the performance they do. The trick is to be in that upper end of pressure yet still remain safe, or suffer diminished performance due to excessively lower pressures. This should be of particular interest to long distance target shooters.
What I have described is a reliable and simple go/no go test that reveals whether or not a loading may exceed the tensile strength of the brass being used.
It is particularly useful in circumstances where, case head web thickness is minimal or case head hardness isn't what it should be, such as after incompetent or clumsy case annealing or having a batch of 'too soft' brass.
If expansion of 0.0005" using this method is seen then it is a definite warning to back off.
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Re: Monitoring for excess pressure-case head expansion best?

Post by animalpest » 19 Sep 2021, 12:14 pm

Oops, I said 2 thou expansion and it should be 0.0002
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Re: Monitoring for excess pressure-case head expansion best?

Post by disco stu » 19 Sep 2021, 3:18 pm

I thought 2 thou was a bit much, figured I would just use the more conservative figures. Who am I to correct you! You're actually more conservative than most books are
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