I seriously doubt this is case head separation but what do you guys think?

[J E Custom]

Wrong again, the headspace increases over the lifetime of of the rifle. Excessive bolt thrust can cause bolt lug setback and a increase in headspace. Oil, grease and water in the chamber can cause excessive bolt thrust and double the normal amount force applied to the bolt face. If the bolt lugs are not lubed this can cause wear and over time the headspace will increase. Hot loads will increase the headspace faster than light or normal pressure loads.

Bottom line, if the rifles headspace never changed after it is initially setting you would not need a Field gauge. Checking headspace, is like checking how much tread is left on your tires. And headspace will increase just like your tire tread depth will decrease with wear.

Why should I care about my rifle's headspace?
http://thecmp.org/training-tech/armorers-corner/headspace/

The three gauges you will encounter are the "GO", "NO GO" and "FIELD". CMP only uses "GO" and "NO GO" gauges but I will describe all three.

The "GO" gauge - is most commonly used when installing a new barrel and reaming the chamber to size. The bolt should fully close on the "GO" gauge, if it fully closes you can be sure you have enough room in the chamber to prevent the cartridge from being crushed during chambering. The "GO" gauge can also be thought of as a minimum safe headspace gauge and the rifle's bolt must be able to fully close with it in the chamber.

The "NO GO" gauge - is used to make sure a firearm does not have excessive headspace. The bolt should NOT fully close on the "NO GO" gauge, if the bolt cannot be closed on the "NO GO" gauge then you know your rifle does not have headspace that is excessive. The "NO GO" gauge can be thought of as a maximum headspace gauge and should not be able to fit in the rifle's chamber with the bolt fully closed. If the bolt DOES close on the "NO GO" gauge, it does not necessarily mean that the rifle is unsafe; it does however show that a further check with the "FIELD" gauge would be necessary to determine if it is safe to shoot.

The "FIELD" gauge - is used to check absolute maximum headspace. If the bolt closes fully on the "FIELD" gauge the rifle IS NOT to be fired and should be considered unsafe to shoot. CMP does not use this gauge because rifles that pass the "FIELD" check but fail the "NO GO" are approaching the point where they will be unsafe to shoot. Our standard for maximum headspace is the "NO GO" gauge to ensure our customers will be able to shoot safely for many years.

I am impressed you finally got it right, but the term Lifetime is the key. If you don't overload the cartridge and do reasonable maintenance
The head space should not ever become an issue If you fire excessive rounds at a high rate you could erode the chamber without high pressure loads.

It is rare for a hunter to ever have this problem But it can happen under certain conditions. The only weapons I have ever seen that a field gauge would close on had 50,000 + rounds through them and started with maximum head space to begin with. It simply should not happen to responsible gun owners. In the military it is not common, but it does happen with rifles because of there service.

My reference was to normal use and care and from one loading to the next. the brass however changes every time you fire it. but Anything can happen and sometimes does. I just don't have any rifle that every change over 1 or 2 thousandths for there lifetime before I re barrel and re chamber or set the shoulder back and re head space.

J E CUSTOM

 

[bigedp51]

I said earlier in a post that if something was wrong with the firearm this could/would happen if the primer could stay out of the case when fired.

Weather we agree or disagree, this is not a usual condition and could be dangerous. another thing, I have tested firing pin strikes by priming only (No Powder) and even though the case still had case clearance it still never backed out.

I have never seen this problem because it does not exist in firearms in good working order or loads loaded correctly. and I'm not fast enough to see the primer pop out and then go back in during the burning of the powder charge. so giving that you may have, I would recommend that you have a gunsmith look at it and an experienced Reloader give you a hand.

J E CUSTOM

So you are saying you know more about reloading than the Sierra bullets testing laboratory.
And you have the audacity to think you are a experienced reloader.

You must have a reading comprehension problem. Try reading the last paragraph below "AGAIN" and not move your lips when you read.

Below 7mm Mauser cases that were made with the case shoulder set back too far. And when fired at lower pressure in a military Mauser the primers backed out. Short cases like this can be fire formed by seating the bullets long and jammed into the rifling to hold the case against the bolt face. I had to do this with new Winchester .243 cases that were .011 shorter than chamber headspace.

The problem with the Internet is we have too many midgets sitting at their computers pretending to be giants.