300 win mag case seperation question?

[rcarter]

I need some help here.  I have been reloading my 300 win mag for years and had a first today.  After one of my shots I opened up the breech and went to extract the case only to remove the base of the shell!     The case had seperated or cracked directly above the belt all the way around.  Prior to loading I had no signs of damage to the case, wear was very minimal as I had only loaded these 2 times, length was good, etc.  Has anyone ever saw this before. 

Out of the 40 rounds I had today at the range only this one was an issue???

[JON8777]

Measure your head space theres that Miikee guy that has a good artical on how to measure head space on the Encore.

Any headspace over 0.006" is "excessive".

[Lone Star]

This is not uncommon with belted cases that are improperly FL sized.  Setting the shoulder back is easy to do if you follow the typical makers' instructions for FL die setup.  You need to set your dies so that you just kiss the case shoulder with your die, not setting it back.  A properly sized belted case will last as long as any non-belted case if you size to headspace on the shoulder rather than the belt.

This is the problem with the above suggestion - the case will still show acceptable headspace on the belt - but will have excess headspace on the shoulder.  Set your FL die with a fired case and you won't have to measure anything.



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[Hopalong7]

This is not uncommon with belted cases that are improperly FL sized.  Setting the shoulder back is easy to do if you follow the typical makers' instructions for FL die setup.  You need to set your dies so that you just kiss the case shoulder with your die, not setting it back.  A properly sized belted case will last as long as any non-belted case if you size to headspace on the shoulder rather than the belt.

This is the problem with the above suggestion - the case will still show acceptable headspace on the belt - but will have excess headspace on the shoulder.  Set your FL die with a fired case and you won't have to measure anything.

Amen!!! Walt 

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[rcarter]

Thanks.  I was wondering about that.  I have checked the headspace before and was perfect.  It makes sense about the die setup with a fired case.  I'll be sure to setup my next setup with them and check them over.

Thanks again.