Checking for Incipient Case Head Separation?

When you get head separations depends on several things:

1. How hot the load is.

2. Brass quality.

3. How much brass is resized. If your chamber dimensions matches your die dimensions pretty closely, then you aren't resizing cases much and won't get head separations as soon.

Some brass in some guns with some loads will be OK for 20+ reloadings while in others you might get only two reloadings. It sounds like you're checking your cases appropriately. The area of the case just above the web should be perfectly smooth. If you feel even a little dip somewhere around the circumference of the case in that area, it indicates the brass is thinning and within the next one or two reloadings you'll probably have a head separation.

and I think I should be feeling something I'm not feeling.

Click to expand...

Pick one you think you should you should be feeling and saw in two lengthwise with a fine tooth hacksaw.

Then you can look inside and see if it has any feelings.

rc

I don't want to say cases are designed to stretch, but stretch they do.

The allowable stretch is about .006", which is the normal difference in chamber headspace from Go to No Go.

When cases are stretched more than .006" they are apt to rupture.

Cases will rupture in mechanisms with a lot of stretch, such as rear locking rifles and will excessive pressures. Cases get stretched something awful in rear locking mechanisms, case life in Lee Enfields is very short.

Cases get really stretched in Garands and M1a's. These mechanisms unlock while there is still residual pressure in the barrel, this is intentional as the designer wants to maximize the amount of time usable energy is available to function the mechanism. While the unlock pressure is below the rupture pressure of the case, pressure keeps the front of the case stuck to the chamber walls as the mechanisms unlocks and opens. The result is that the case is stretched and seldom survives five cycles of reloading and shooting.

As you are shooting a front locking bolt rifle, as long as you are only bumping the shoulder back a couple of thousandth’s each sizing, your cases don’t have to stretch all that much to fill the chamber on combustion. Cases can last, virtually forever, the life limits are determined by brass flaws, case neck cracks and primer pocket expansion.

Here are examples of 6.5 Creedmoor cases that were oversized. The poster had not set up his dies with case gages and was getting early and severe case head separations.

The allowable stretch is about .006", which is the normal difference in chamber headspace from Go to No Go.

Click to expand...

ONCE.

The allowed range is NOT set up accounting for reloading.

If you want to maximize brass life and reduce the chance of separation you need to know how far you are moving the shoulder back when resizing.

If you neck size (or do not move the shoulder at all) it will eventually become hard to chamber the brass as the shoulder gets closer and closer to the chamber length. Spring back on firing decreases as the case gets worked and the brass becomes harder.

At that point you can make sure you set the shoulder back using a bump die or a full length sizing die.

Even in rimmed cases brass life can be extended by using the shoulder to headpiece the cartridge after the initial firing.

Pick one you think you should you should be feeling and saw in two lengthwise with a fine tooth hacksaw.

Click to expand...

this.

Its no guarantee that the brass will not break, but it will show you if there is something to feel or not. When I had the same fears about some 223 brass, this was what I tried. (brass checked out ok)

I guarantee it ...

If you want a guarantee that you won't get case head separations, I suggest using the Digital Headspace Gauge. If used according to the instructions, your handloads will fit your chamber perfectly, and you'll never see another case head separation - never.

It works on ALL different calibers, and it doesn't require special bushings or attachments.

Back in the 80's I was already using the paperclip on my 300 Win. cases. It worked pretty good for me. When things start happening inside the case that paperclip does a pretty good job of telling you so...Remember, at that point the cases could very well still look perfectly good from the outside.

j2crows .....

You're right. Case stretching begins inside the case.



However, it should be avoided by measuring (and reducing) the chamber clearance of your handloads at the shoulder.

This is probably the primary reaosn I tumble my brass well, it makes it so much easier to resognize the first signs of separation.

Gamestalker ......

The best way to be sure of your brass (above the web) is to "measure" it with a tool like the RCBS Case Master. Otherwise, you'll be throwing away brass that's perfectly good.


Belted and rimmed cases are especially easy to get case head separations. This is because NEW brass headspaces on the belt and the rim - not on the shoulder. These cases take a real beating on the very first shot. After that, it's best to minimize your shoulder clearance - again by measuring.

rcmodel said:

Pick one you think you should you should be feeling and saw in two lengthwise with a fine tooth hacksaw.

Click to expand...

That's what I'd do. You may not have any problems at all. But if you do see a ring of thinning material you can drag the tool you made across it to see what you should have felt.

Then you can look inside and see if it has any feelings.

Click to expand...

I hope we didn't hurt its feelings when we sawed it in half...