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Old January 7, 2007, 01:55 AM   #1
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Rifle brass modes of failure

I was reading up in the newest Hornady manual and was looking over the different methods for headspacing (rims, belted, shoulder). It sort of made it sound like rimless rounds headspacing on the shoulder are the only ones really prone to casehead separation with it sometimes occuring in belted magnums.

If that's the case, how do rimmed rounds like the .30-30 usually tend to fail? Split necks? Do neck-sized only rimless rounds still separate case heads nearly as often?

I was just asking cause I'm fairly new to rifle reloading (done alot of pistol), and as I understand it, a case-head separation can be pretty catastrophic.
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Old January 7, 2007, 03:50 AM   #2
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Anything pre-fired in a chamber and then neck sized will Have a much greater resistance to head-case seperation because of the tighter fit in chamber..Im not sure on the other stuff.I think belted magnums have the biggest chance of failure from what ive read and you have to check the brass often in
magnums like the 300Winchester mag(near the belt I believe)..I wouldn't think a rimmed case would be much different than a rimless but I might be wrong..
Not having your dies adjusted properly can create the biggest headspacing problems(getting your shoulder bumped back just enough and not to much).Adjusting the dies so you get your ammo sized to the minimum that still gives you safe operation is best(for semi's like the ar15).I would mostly always use a collet neck sizing die to eliminate headspace issues if I had a BOLT action.Brass will last longer too
Just some thoughts.Im sure someone with more knowledge will comment on this subject.

Well actually when I think about it ,I think a rimmed cartridge would do better because your firing pin cannot force your case forward(because of the rim).That would keep your brass from being forced to flow backwards,forcing the head of the case to stretch to the bolt face(like in a rimless cartridge)..That makes sence to me anyways
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Old January 7, 2007, 09:58 AM   #3
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A case head seperation usually only results in an inoperable rifle until the front half of the case can be removed. It CAN burn a ring in the chamber IF it seperated enough for hot powder gases to "get to" the chamber wall.

Usually there's just friction holding the front part of the case in the chamber. One trick often used to remove it is to take a bronze cleaning brush, jam it into the neck of the remaining case piece from behind, then pull it back out. It should provide the necessary force required to remove the brass. Inspect and clean the chamber, you're back in business!

As for which case design has the most problems with case head seperation, they all can and do! IF the reloader sets the sizer die wrong for that particular rifle, ANY type of case can be made to seperate.

When I first got my 7X30 Waters, I had trouble with CHS. It is based on the 30-30 case, but with a much more defined shoulder. I was setting the shoulder back too much, CHS happened at the second or third reloading for some cases. I had to follow some advice from the gunshop owner on how to set the FL die. Taking a shell fired in my chamber, I backed out the FL die 2 turns from it's previous setting. I then sized one case, then tried to chamber it and close the contender action/barrel. It would not close! Duh, of course not! Then turning the die down 1/4 turn at a time untill I could only close the barrel with a sharp SNAP! I then locked the die ring at that point, it was more than a half turn too tight!

Firing that too short case before caused the shoulder to move forward under chamber pressure, with the rim holding the head, the web HAD to stretch. I had to trim a LOT with those cases, that SHOULD have tipped me off that something was amiss! After properly setting the FL die, the cases only grew slightly, not requiring trimming until the third firing!
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Old January 9, 2007, 11:28 AM   #4
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I have overloaded dozens of cartridges hundreds of times rimmed and rimless. I have had one case separate, a 10mm. It separated right in the middle. I don't re use overloaded brass.

I bought an Arisaka 6.5mm with a case separated already in it.

What does it all mean?
Separations are due to stretching from more than one event, probably repeated full length sizing and reloading.
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Old January 10, 2007, 12:48 AM   #5
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Neck size if you're loading for a bolt or single shot and head separations will be of no concern. With fireformed brass, you will have perfect headspace.
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Old January 10, 2007, 05:45 AM   #6
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In all my years of reloading I've never had a case seperation. However I wonder if there are any warnings signs before that happens. Aside from a crack inside which I generally look for with a bent paper clip?
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Old January 10, 2007, 09:10 AM   #7
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I've had a .270 case separate without any catastrophic consequence (not to say you should look forward to it).

Using a bent paper clip, I find it difficult to determine the internal "ring" with certainty. Most often by the time you can feel the ring you can see one on the outside of the case. Another reason for looking the cases over as you prepare them - so needing to clean out the tumbler media from the primer pocket is not a bad thing.

Very early you can see a "halo" around the web area - a slightly shiney ring that makes you wonder if that's it. Fire it again and you may see it enlarge; if so, that's the start. Fire it again and it may crack in one area and the ring becomes more apparent.

I believe anyone who experiences a case separation by surprise hasn't properly inspected the cases before reloading them. I have about a half dozen cases in various stages of separation that I've kept just for example in local discussions.
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