Thread: How do you know when your brass is kaput?

That's a good tip. I wonder what causes that thin spot in that specific point.[/QUOTE]

The case neck and body is pressed out against the chamber from firing pressure and cannot move reward. The case head-web is thicker and doesn't/should not expand and so doesn't grip the chamber and is forced reward against the bolt,hence the stretch in that area.
This is why its important when full length sizing to size to your chamber and not over size or it will stretch excessively in this spot reducing case life.
Any good loading manual is full of this and lots of other info

thin spot, in general engineering, I say that because while I have considerable engineering and some combustion knowledge I have none specific to ammo and explosions (though an explosion is really just a very fast [mostly] un-controlled fire), so several possibilities,

The flame from the explosion will have a "front" as it goes off even and explosion takes time to happen, sort of like a weather front as the flame burns it maybe that that front impacts the wall just there so its erosion, and/or the flame front's temperature is causing a localised change in the metal like its being softened more than else where and/or its the highest pressure point hammering it thinner. You could send a cross section away to get the metal in that area put under a microscope to see if there is any sort of change.

c) Something in the way a full die is working that causes a thinning just there.

If you really wanted to know, a microscopic inspection might yield clues, in fact I suspect you would indeed see from that.

Also from what I can read some case manufacturers cases have a thicker wall, so they may cost a little more but last longer. I didnt know about this effect so that will probably send me in the direction of looking for a high quality case with the thickest walls as a starting/testing point.

thanks!

Originally Posted by veitnamcam

That's a good tip. I wonder what causes that thin spot in that specific point.

The case neck and body is pressed out against the chamber from firing pressure and cannot move reward. The case head-web is thicker and doesn't/should not expand and so doesn't grip the chamber and is forced reward against the bolt,hence the stretch in that area.
This is why its important when full length sizing to size to your chamber and not over size or it will stretch excessively in this spot reducing case life.
Any good loading manual is full of this and lots of other info [/QUOTE]

That makes a lot of sense put like that. I'm amazed at the massive forces going on there.

There are two 7mm08's in the family I load for, so I have to full length size enough to fit in both rifles.

@rimfire I did some digging as your Q interested me also (Ie google and youtube) and I saw mention of 30 reloadings+ but that might be just necking for bold actions.

Also it seems the fruity loop americans are buying 223 and 7.62x39 like crazy so those rounds and reloading parts (that were the cheapest) might become un-obtainable or obscene prices. Ive seen an email saying that russian made 7.62x39 is all but gone in NZ and no future date for delivery. Pity as I fancied a CZ in 7.62x39....

Thinning, yes that would make sense, occams razor, simplest answer is usually the answer.

regards

Originally Posted by RimfireNZ

Some of my 7mm08 brass is coming up on 7 reloads (and unfortunately got mixed in with some newer stuff a little while ago) and I was wondering when do you guys call it quits on brass?

Do you ditch it after a certain number? Or do you look for certain signs?

One of the dodgey guys at the range waits until there's a big bulge/ring about a cm from the back of the round

I do always check the necks and cases for cracks, I check for bulges. So far nothing, and I reckon (from what I've heard) I'll get ten reloads out of the 08 brass, but curious to see what you guys do.

The stain in your undies will let you know you should have chucked that one last time