Incipient Case Head Separation

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TenDriver

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I saw a ring near the case head of a few of these and thought, "separation!" Since I figured the case was headed to the recycle bin anyway, I decided to let it meet my Dremel. Turns out the line on the outside is where the thicker brass is. No marks on the inside.

Case is an FC 270 Win. Here's the pics. ImageUploadedByTapatalk1385335054.800847.jpg
ImageUploadedByTapatalk1385335067.260482.jpg
 
I believe that the line on the outside of your case is from your resizing die. :)
 
Yes, in this case it was.

Like this .35 Remington case. Smooth as a babies butt inside.

attachment.php
 
Nope. It is where the brass expanded a little in a chamber a bit larger than the base of the case. Not a big deal.

Case separation happens higher up.

J.
 
In my world, that brass wouldn't be any where near my recycle bin. For .270 win, I average upward of at least 10 cycles off my brass. And depending what head stamp, I will get 12-15 cycles from it. It's mostly about how close head space is maintained, and avoiding over working it when resizing it.

GS
 
gamestalker said:
In my world, that brass wouldn't be any where near my recycle bin. For .270 win, I average upward of at least 10 cycles off my brass. And depending what head stamp, I will get 12-15 cycles from it. It's mostly about how close head space is maintained, and avoiding over working it when resizing it.

GS
Click to expand...

I was going to load it once more and check, but decided to cut one open and check out the inside. Figured I'd put the pics on here just for the heck of it.
 
Thanks for posting the pictures. It helped me when I look at mine and try to tell the difference between normal and a problem waiting to happen.
 
I haven't shot my way through all my rifle brass yet so I haven't had to deal with the separation problem. Is it something that only happens with max-powder charges or do all cases eventually go?
 
It is caused by case stretch.
The front of the case being thinner, grips the chamber tightly while under pressure, while the rear thicker part slips rearward to reach the bolt face. Where the difference comes from is case stretch.

More often caused by sizing too far and pushing the shoulder back to far, creating artificial excess headspace.

If you size to minimum headspace the bolt will just close on, case stretch & separation isn't going to happen until a bunch of reloading cycles.

rc
 
Havok7416 said:
I haven't shot my way through all my rifle brass yet so I haven't had to deal with the separation problem. Is it something that only happens with max-powder charges or do all cases eventually go?
Click to expand...

It does shorten the life of the brass using max loads, but the most common cause is like was already said, over sizeing brass.

Old brass that is kept to the proper headspace and shot a lot, will "generally" get split necks and/or loose primer pockets.

DM
 
Cool, thanks for the info. I have been a bit skittish with my rifle brass for this reason and never thought to ask the question!
 
You have two problems with hot loads. The case head will stretch and open your primer pockets and the "feel" seating the primers is a indication your pocket has enlarged.

This will let gas flow around outside of the primer cutting your bolt face.

Once primers get loose you can switch to the Russian Wolf primers which are larger diameter and seat more snugly in base.

Now head expansion can be treated several ways. Lets take 30.06 for instance. Every factory round of 30.06 I have ever measured is .465 diameter measured .200" up from rim. Chambers run .471-.473 thusly if your die sizes down to say .466 then you are going to get a lot of brass being overworked.

Fortunately the die vendors put out dies with dimensions all over the place. I have four sets of 30.06 dies that size as follows:
.466
.468
.469
.4705

The first three are unaltered factory dies and the .4705 was a .469 die I polished out to .4705 for the big jumbo factory chambers.

When I rebarrel I have two custom 30.06 chamber reamers that give me .467 and .469 chambers thus I use the .466 on the .467 chambers and .468 on the .469 chamber.

Next problem to be considered is factory commercial cases tend to have soft heads as they are basically designed to be shot and forgot and some can only be reloaded twice and others up to maybe 7 times depending on hot your loads are.

Unless there is a justification for hot loads I think you will find you will get tighter groups by conducting a step load series and finding one of the sweet spots for that caliber in your rifle. This will increase your brass life.

LC and other military arsenal 30.06 cases have much thicker case walls and much harder heads which will take many more loadings. For instance I have one 30.06 LC match case I have loaded 157 times and it is waiting to go some more.

You should get similar results in 308/7.62 brass though you will find US military 7.62 will measure .468 at base where the commercial I have measured is .465.

Any time I am around a flea market and I set a set of dies for 5.00 to 15.00 I pick them up on the chance I can use them as is or modify them for longer case life.

If you plan on doing lots of shooting the rest of your life you might consider a custom reamer. They will run about 225.00 but the savings in brass will pay for the reamer and the reamer is good for many barrels down the road.

222 Rule: When I order a custom reamer I measure a new factory round at the base and neck. I order the dies .002" larger than the base and neck. I headspace my rifles on a GO gage so the brass does go forward at the shoulder over .002 on firing. Thusly no dimension moves over .002" on firing.

Not all the vendors will want to make custom reamers but my buddies that built the Secret Service Sniper Rifles told me Manson would and thusly I get mine from Dave.
 
Hummer70,

The shell holder deck height is .125”, there is no sizing of the case head below the top of the shell holder plus the radius of the die. The case head thickness of commercial R-P 30/06 is .260”. There is case head protrusion and unsupported case head, two different measurements. When measuring case head diameter the reolader must understand there is a maximum case head expansion every time the case is fired. An acceptable amount of .00025” as a rule of thumb. If a case head expands from ,468” to .471” in one firing the case head expansion would be .003”. The .003” would indicate the case head is expanding 9 times greater than recommended over factory loads.

When measuring the diameter of the case head it is suggested the rleoader use special tools.

F. Guffey
 
Last edited:
Just posting this here for n00bs like me (who are extra-obsessing over making sure things are safe).

If you're using the Lee chamer/deburr tool on 223 Remington cases, just be aware: During the work on the _outside_ of the case mouth, the base of the tool can put a small scratch in the brass a little north of halfway down the case body.

I freaked myself out momentarily thinking I had a run of cases that were separating have seen the 223 separation earlier in this thread.

Unashamed at my error, because better safe than sorry. :)
 
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