Case head separation what are the signs.

[pbonura]

Just inspecting some cases I full length sized and noticed a small ring at the bottom of the case around the case at the bottom. Is this a sign of case head separation. My guess is when I full length and sized the brass I did not set up the die correctly. I am a rookie so any advice is appreciated. If these cases are showing signs of case head separation should I just not use them.

 

[LUTNIT]

Neck is at the top, where the bullet seats. What you describe is case head separation.

The ring is a stretch mark where the brass stretched. I don't like full length sizing brass with those marks as it will most likely stretch in the same place again when fired. With bolt action guns I only neck size I don't really care since the cases are already fire formed so any case head stretching should be more or less finished.

If the head separates in a semi auto it can be pretty disastrous. There are a lot of pics of rifles that are absolutely destroyed because of this. In any manual action gun (bolt, pump, lever, single, etc.) you can end up extracting the head and leaving the rest of the case stuck in the chamber. Sometimes a cleaning brush can get it out but I bought a broken case extractor tool for 303 British because case head separation is so common in old British army rifles (and the tool was only $10 on eBay).

If you full length resize after every firing the shiny ring will show up eventually. If it shows up on first firing you may have headspace issues with your rifle. Chances are the ring was there before you resized but you may have just not noticed.

 

[Baribal]

A shiny ring is somewhat normal about 0.200" above the case head, as that's where the material will expand to reach the chamber wall (the head itself is solid). Too much expansion is bad, though.

Use a paper clip or any kind of rigid wire, bent the end in a "L" shape and by running the tip of the "L" inside the case in a slow going motion, you will be able to feel that the sides are not linear.
A picture worth a 1000 words.

 

[Johnn Peterson]

A shiny ring is somewhat normal about 0.200" above the case head, as that's where the material will expand to reach the chamber wall (the head itself is solid). Too much expansion is bad, though.

Use a paper clip or any kind of rigid wire, bent the end in a "L" shape and by running the tip of the "L" inside the case in a slow going motion, you will be able to feel that the sides are not linear.
A picture worth a 1000 words.

That says it all. Well done.

 

[ted_dent]

A shiny ring is somewhat normal about 0.200" above the case head, as that's where the material will expand to reach the chamber wall (the head itself is solid). Too much expansion is bad, though.

Use a paper clip or any kind of rigid wire, bent the end in a "L" shape and by running the tip of the "L" inside the case in a slow going motion, you will be able to feel that the sides are not linear.
A picture worth a 1000 words.

That's a great pic. A ring at the base of the case is normal for full length sized cases as that is where the size die stops. However it is just cosmetic as the die tends to 'polish' the case as it sizes it but doesn't polish the base of the case which does not go into the die, hence it looks like a ring. As a case head starts to separate the stretching creates a shiny ring as well but it tends to be longer and more shiny than the ring caused by sizing. If in doubt try the paper lip trick. I saw one old enfield rifle where the headspace was so excessive that cases showed serious stretching after just one firing.

 

[ATOM]

phonura - If you are in doubt, you could always take a minute or three and section one the cases in question with a file or grinder. Baribal's most excellent photo shows what to look for.

 

[dthunter]

Good job baribal! The picture is great!

 

[bigedp51]

The factory loaded Winchester .303 case stretched and thinned .009 on the first firing below.

The RCBS Case Mastering Gauge works better than a bent paper clip.

The red and yellow areas below are the high stress points, and you can see below the rear of the case stretching to meet the bolt face.

And the amount of head clearance is what governs how much the case will stretch and thin in the web area.

 

[pbonura]

Thanks. Tried the paper clip trick on the federal brass and everything looked perfect. The s&b I going to double check again as some of the cases show more marks. Great thread thanks for the responses and that paper clip trick is a great idea.

 

[HIGHRPM]

Great info guys, thanks !

 

[*MALICE*]

It's when you see the black line inside the shiny ring is when you are on the hairy edge of a case head separation.

You will get a plain shiny ring (burnishing mark) on most cases just because of the die not touching the case all the way to the bottom of the head.