case separations - Rossi carbine

[Longwalker]

I have run into a problem with some .357 magnum handholds shot in my Rossi carbine. The cases are a batch of used brass I bought on the EE. I do not know for sure if they are all once fired or if some are older. Most shoot and function just fine, but about one in fifty cases are separating about halfway and only the back half ejects. I have several hundred loaded, so I'm not highly motivated to pull the bullets and discard the cases. Loads are moderate pressure, 158 grain cast gas check lead alloy bullet over enough H4227 for 1400 fps from my rifles 20" barrel. I don't believe I am stressing anything much. I have shot the loads over a chronograph and velocity of a separated case is the same as the rest, so I have not made the dreaded "double powder charge" loading error. It looks like a few of the cases might just be old and worn and mixed up with newer 1x cases.
So my question is - has anyone run into unusual case failures in their Rossi carbine? Is there something I am missing? The back half of the case appears to be sealing the breech from escaping gas. I shoot with safety glasses on and have not detected any gas escaping back to hit me in the face, after about half a dozen case failures. I had decided to just shoot up the batch during casual plinking sessions and then discard the whole lot of cases. Am now wondering if this is too risky.
Experienced loaders of handgun cartridges in carbines, what say you?

 

[freedomintheskies]

Sounds like the brass is ummm... experienced.

For safety, I would pull the bullets and check the brass for the incipient case head separation telltale ring inside the case about 1/4-1/2 inch from the web of the case.
Use a straightened paperclip and drag it up the inner wall of the case. Any case that you notice a "dip" simply discard. The remainder should be fine.
I do this on all my cases now, since it happened to me on a batch of "once fired" .308 cases I purchased online.
Cheerz.

 

[bigedp51]

A cartridge case is a expendable item and you need to ask yourself if you want to take a chance and damage your rifle. On top of this you do not know how many times the cases you bought were fired. And for all you know these cases could be range pickup brass.

When a case separates it means the case had to stretch to meet the bolt face. Head clearance is the "air space" between the bolt face and the rear of the case and the distance the case can stretch.

Some carbide dies overwork the brass by excessively reducing case diameter. And Lee dies are noted for sizing cases more than other brands. Meaning this can work harden the brass faster and cause case failures.

The only case head separations I have ever had were .303 British and this did not cause any high pressure gas etching or erosion of the chamber.

If it were my rifle I would want to know how much head clearance my cases have and what is the headspace of the rifle. This would help to determine if the rifle has anything to do with the case separations.

You can check your head clearance with a spent fired primer and a new or full length resized case.

First take a case and measure its over all length and write it down.

Next start the fired primer in the case just using your fingers.

Now chamber this case and slowly close the bolt and let the bolt seat the primer and then remove the case.

Now measure the case again from the base of the primer to the case mouth and write it down. The amount the primer is protruding is your head clearance.

Subtract your first case measurement from the second and this will be your head clearance in thousandths of an inch.

Now measure your rim thickness and add this to your head clearance measurement and this will be your actual headspace.

By doing this you will be able to determine if you just have some bad brass or if your rifle is letting the cases stretch excessively.

Bottom line, I have never had a pistol or revolver case separate and I had a Lee carbide .357 die that made my cases very Coke bottle shaped and I stopped using it.

So do you have bad brass, were the cases being over worked during sizing or does your rifle have excessive head clearance/headspace.