Unusual case separation?

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243winxb .....

I'll bet that if we saw a picture of the OPs fired case, it would show a sign of case head separation a bit farther up the case.

Most manufacturers make their cases with a thick transition to the case web (like in the picture). That prevents a "stress riser" from causing case head separations all the time.

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Not likely ...

243winxb .......

This is a very common handloading problem with belted magnum calibers. I've never seen this symptom caused by a chambering problem.

The questions from this post have helped me to expand a page on my website. Take a look at the Reloading Questions page on my website.

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This posting is getting way off topic when people think a full length resizing die will take the place of proper fireforming. Innovative your die has nothing to do with fireforming and cases stretching in the web area on the first firing.

Now ask yourself why the OP left this posting and started another.

The problem is headspace/head clearance, fireforming, cartridge case quality, quality meaning maintaining proper case dimensions during manufacturing.

Innovative your reloading die will not correct headspace, small cartridge case base diameters, thin case walls or fireforming techniques on the first firing.

It is one thing to try and help this poster, it is another thing trying to make money off your product and not say a word about fireforming techniques which would prevent the case stretching in the first place. By simply seating his bullets long and jamming them into the rifling on the first firing the case would have been held against the bolt face and not allowed the case to stretch on the first firing.

Innovative, I'm giving advice away for free, what are you doing?
 
However, for practical purposes the 50,000+ PSI in your chamber makes your fired case fit REAL close.
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Only till the pressure drops away.

Brass is elastic, and even 0.0001 is enough.
 
All good points to ponder, and even some sound seriously discriptive of what I'm experiencing with this.
I took some measurements of fired brass that was bumped when before reaching the limits of the chamber:

At the very top edge of the belt on the brass that failed was .512". On brass with that had been properely maintained at the shoulder it measured in the same spot .508" - .510"

So I'm now thinking that it was an effect of no where else to flow/stretch causing the brass to buldge in the only place left to expand.

Having never experienced this before, I don't feel it is brass quality issue, though I do agree the good stuff is going to probably hold up longer.

So the fault clearly seems to be mine because I didn't set the shoulders back, and instead force fed them into the chamber, they were a super tight fit. My other post shows some comparison loads that probably support this.
 
Just the facts ...

bigedp51 ......

My thought is that the OP originally asked if his tight fitting handloads (that failed above the web) were typical for belted magnum calibers (not a 303).

I replied with a cut-away picture of a belted magnum case, and explained what appears to have happened. Other technical questions (especially yours) were helpful for me to explain things in greater detail. You are right that our collet die doesn't correct headspace, because it was not designed for that purpose. I designed it specifically to only reduce case "diameter" above the belt when needed.

You asked "What have I done for the shooting sports?"

Well, my first goal is to promote the shooting sports, and support shooters. Read my website, and you'll see over 130 pages of technical handloading and shooting info that is designed to help fellow shooters. (Only one page has items for sale.) So far, it has taken almost 10 years to create www.larrywillis.com and it gets visited by well over 800 shooters every day.

I've also worked in the shooting industry for over 10 years, where I designed (and patented) 2 reloading tools that are currently used by more than 5,000 shooters worldwide. In that time, I've kept my prices from going up one dime.

- Larry

P.S. There's really nothing wrong with saving and creating jobs.

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gamestalker

At the very top edge of the belt on the brass that failed was .512". On brass with that had been properely maintained at the shoulder it measured in the same spot .508" - .510"
Click to expand...

Your next question you should ask yourself is how thick is the case wall on these two case you measured at this point. If the case wall was thinner it would cause the cases to stretch more at the thinner and weaker point above the belt.

What you are saying is your cases were so tight fitting in the chamber that forcing the bolt closed caused the cases to bulge and forced a case head separation? :confused:

I'm telling you your case stretching,thinning and case head separation started the first time you fired your cases causing your weak spot above the belt.

Without checking and measuring your cases in the web area before and after shooting you are doing nothing more than guessing about your problem.

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Below is a greatly exaggerated example of creating a false shoulder on your cases to hold them against the bolt face to fireform them, this will keep the cases from stretching on the first firing and you will NOT have a weak point to compress as you stated that caused your case head separations.

Below the case will headspace on the false shoulder which will hold the case against the bolt face when fireforming. This will prevent the case from stretching and thinning and prevent case head separations. The actual false shoulder location will depend on your chamber headspace and the location of the shoulder of the case

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Innovative

I didn't ask you "What have you done for the shooting sports?".

I asked you how your reloading die was going to stop the case from stretching on the first firing.

I asked how your die had anything to do with neck sizing only. :confused:

And I asked how your die made up for defective cases and bad quality control.

This is a case stretching posting and not a posting on how to full length resize a 7mm Remington magnum that has been neck sized only. You have side stepped my questions and danced around this problem promoting your product.

My statement to you Innovative is your more concerned with selling your dies than fixing the problem at hand, and that is case stretching on the first firing and creating a weak area on the case. ;)
 
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Innovative

A cartridge case can stretch longitudinally and radially when first fired or in length and width and it doesn't matter what "type" cartridge case it is. If the case doesn't stretch in the base web area when fired it will not have a weak spot at that location to fail. This problem is caused by the upper section of the case gripping the chamber walls and the rear of the case stretching to meet the bolt face.

A full length resizing die no matter how well made can not fix a weak spot in the base web area of a cartridge case that is already damaged from stretching.

If you want people to understand what you are saying then send a free die to gamestalker and see if it solves his problem and stops his cases from stretching on the first firing before his cases even get close to your die. ;)

The key words are "headspace" and "head clearance" when it comes to case stretching in the base web area.

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bigedp51 ......

Your illustration correctly shows how a poorly fitted barrel causes a rimmed case to rupture. That's the same for a belted case. However, when a rifle barrel is correctly fitted, and handloads fit the chamber with near zero shoulder clearance, case head separations are avoided.

No die is designed to fix weak cases. However, when a FL (or a NK die) is used accurately on a belted case, it can reduce the thinning and weakening of cases. Those belted cases that are damaged in the first firing can be "managed" my measuring with the Digital Headspace Gauge to limit shoulder clearance.

I don't send free gifts to anyone, and I'll bet you don't either.
 
Innovative
Your illustration correctly shows how a poorly fitted barrel causes a rimmed case to rupture.
Click to expand...

Innovative you are incorrect again, my illustration shows what happens when you fire a commercial cartridge case in a long, fat military chamber and a cartridge case that wasn't designed to military specifications.

I also mentioned quality control of cartridge cases Innovative, below Remington can't even meet SAAMI minimum standards for the shoulder location of the .303 cartridge case. This makes me wonder where the OP shoulders were on his 7mm Rem Mag cases and if the belt and web were correctly made and within tolerances. And this is the main thrust of my postings here, case dimensions and quality.

It has nothing to do with the noted and praise of your quality products Innovative. And by this I mean your quality dies will not fix defective cases that split just above the belt line, or cases not properly fireformed. ;)

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Again, the top military case is made to design specifications and the bottom Remington case fails.

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Our discussion here is useless Innovative, the OP here does not have the gages necessary to even find his problem. My apologies for being a little grumpy in this posting, I think my underwear might be too tight. But it is a two way street Innovative and some of your comments were a "little" irritating. ;)
This posting has gone beyond useful its shelf life.
 
bigedp51 .....

Sorry about my comment way back in post #19. I can see how that might have been taken the wrong way. No harm intended. Although I have reloaded since the mid sixties, my experience with belted magnum calibers was "a bit limited". There's nothing wrong with that, because nobody has all the answers. I just never had interest in belted calibers until a good friend gave me a new Browning 300 Win. Mag. back around 1995.

mrbro .......

The sharp edge on a case shoulder could "influence" a stress riser during brass movement, but I've never seen any actual damage in this area. Case problems usually occur farther back on the case as seen in the pictures from bigedp51. However, the early Weatherby magnums were on the leading edge of maximum performance, and that might explain why they rounded the shoulder on their cases - or - it could have had something to do with marketing (product recognition).

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Innovative, thanks. When I replied last night I said shoulder when I meant to say belt. I was thinking of the junction where the belt meets the body. Any thoughts?
 
However, when a rifle barrel is correctly fitted, and handloads fit the chamber with near zero shoulder clearance, case head separations are avoided
Click to expand...
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Just about every gun has cartridge clearance to allow for manufacturing tolerance of the gun and ammunition.

In weapons with less force available to close the action, more clearance is often required (semi auto, lever, etc) for reliable operation.

If you allow the case clearance to actually get close to zero, you are very likely to have some rounds that will NOT chamber correctly.

Every measurement has an error, and even if you checked 10% of the cases by measuring you need to make sure the error in the measurement is accounted for.

If the measurement error was plus or minus 0.001, some cases would be 0.001 OVER length.

To account fr tolerance issues the clearance is increased.

By setting the clearance at 0.002 in, an error of plus or minus 0.001 in the measurement results in the cases being 0.001 short to 0.003 short of the actual chamber size.
They will all chamber.

If the chamber measurement is plus or minus 0.001, better add some more clearance for that.

The clearances needed for reliable operation are going to cause case stretching with each firing.

There is no practical way to avoids it.

All we can do is try to minimize the effect, and keep it to a reasonable number to ensure brass life.
 
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