Found a piece of brass that shows groove inside with paper clip test, what do I do with the rest of the brass from that batch about 150 pieces 7.62x39s? OK keep loading them or should scrap the lot. I check every piece with paper clip. They are reloaded twice in reduced load (6 gr 700X and cast bullet) and twice in full power (starting load). Bolt gun only. I did not expect the brass fail so soon. I tend to consider the bad brass is a fluke, the primer pocket is tight and no split on the neck. Originally I thought I would make 4 full power loads then only use for reduced load with cast bullets. 7.62x39 is not high pressure round!
paper clip test then what!
- Thread starter HankC
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Fine Figure of a Man
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I would keep loading them.
Scooter22
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Possible problem is using the reduced load brass then loading full power. Sometimes the reduced load can push the shoulder back because it doesn't have enough pressure to completely seal the case to the chamber wall. So the pressure gets by the neck and pushes the shoulder back creating more head space for that case. Now loaded with a full power load the case gets kicked forward from the FP impact fires and the case isn't supported by the bolt. So it stretches back. I'd toss any brass that you feel a groove in the base of the case. I wouldn't full length size them Just neck size and use standard loads. Or you can use them for the reduced load but I wouldn't full length resize the. Check them again after another firing. You could have just a bad case and found it jmo Good luck. (I need a x39 bolt gun.)
CLP
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People are going to have differing opinions here on this question. Personally, I chuck the whole lot when I have incipient signs of failure. I also never worry about case head separation. Of course, you're shooting these in a bolt gun. Since I do my shooting in ARs (5.56 and 308), M14, and Garands, I don't take the chance. If I were shooting them in a bolt gun, I'd have more confidence to squeeze out another loading or two.
Incidentally, interesting choice of cartridge for a bolt gun.
Incidentally, interesting choice of cartridge for a bolt gun.
243winxb
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The cast loads may expand the case body outward, pulling the shoulder back. And /or the firing pin strike can set the shoulder back also. This produces excess head clearance. The cartridge has a sloppy fit in the chamber.
When high pressure loads are fired, the brass stretches.
Keep brass separated between cast and full power loads.
I would keep checking and shooting the brass. But only with good eye protection.
When high pressure loads are fired, the brass stretches.
Keep brass separated between cast and full power loads.
I would keep checking and shooting the brass. But only with good eye protection.
Nature Boy
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What does the outside of the case look like. Is there a line forming in the same area?
If you have a dremel with some cut off wheels you can cut the case open and see if it is actually about to separate. Then you can make the call about the rest of your batch
If you have a dremel with some cut off wheels you can cut the case open and see if it is actually about to separate. Then you can make the call about the rest of your batch
Charlie98
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FROGO207
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If you found one bad brass that could be just defective. You did check the others so I would load them again after a partial full length resizing or neck sizing if you have that die, and see what the results were after shooting them. If several more (~ 15-20%) show up bad then I would scrap the lot. The partial full length resizing is just sizing the shoulder back enough that the brass will chamber with not a lot of pressure used to close the bolt. Then size all the brass that way and reload as normal after checking brass length and trimming as necessary. This should keep the brass from getting that ring. Using a bolt gun is a lot safer than a semi auto if you do have problems and you could shoot the remainder until the ring appears but personally I would not take that chance if there were a bunch more rings show up. YMMV
armarsh
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See above ^ Learn to bump the shoulders back only .001 or .002 to help prevent brass stretch in your bolt gun.
But I'd keep shooting them. It is not that uncommon to have one or two that are much worse than the rest.
But I'd keep shooting them. It is not that uncommon to have one or two that are much worse than the rest.
The reduced load with 6 grain 700X does expand the brass that I need to press the brass down in full length sizing. The rifle chamber is a "tight chamber" that I cut the chamber myself and just a bit over min head space. I built this bolt gun on a Mauser action. I shoot brass case in my bolt gun and leave steel cased 7.62x39 to semi!
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WestKentucky
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Check the brass carefully. Toss the ones that fail. Load the ones that pass.
Yes the outside does show a line but not obvious enough that I would catch it first without the paper clip test. I did cut the brass open to inspect how bad it is, the ring inside is not all the way around, so is the outside line. Now I learned that I need to turn the brass when I do the paper clip test! I checked rest of the brass again by turning the brass when checking.
243winxb
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Make, model?
Scooter22
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7.62x39 is not high pressure round!
Doesn't matter what the pressure is if your having a head space issue. If the case is getting blown out to far causing excessive stretching in the case head and your FL sizing them back down you'll get separation eventually. Check your fired cases against the FL resized ones to see how much difference there is.. Maybe your die is out of spec and making them to short.
The reduced load with 6 grain 700X does expand the brass that I need to press the brass down in full length sizing
If you try and chamber a fired case will it go in? Usually they will in a bolt gun.
Doesn't matter what the pressure is if your having a head space issue. If the case is getting blown out to far causing excessive stretching in the case head and your FL sizing them back down you'll get separation eventually. Check your fired cases against the FL resized ones to see how much difference there is.. Maybe your die is out of spec and making them to short.
The reduced load with 6 grain 700X does expand the brass that I need to press the brass down in full length sizing
If you try and chamber a fired case will it go in? Usually they will in a bolt gun.
If I find a case with the stretch ring with a bent wire feeler method, then I look more closely. I use a pen light to look inside the case. You can see the shadow of the stretch ring if it's bad. Some size cases I got advice to use an otoscope that a doctor uses to look into your ears. That works well also. I shine a penlight into the case mouth and sometimes into the flash hole and look into the case mouth. I've found stretch rings down in the usual place near the case head and some with stretch rings up near the shoulder mostly where the annealing stops. I've bought military once fired brass in 1000 round lots and typically find from 5-25 per thousand with some stretch rings and they get scrapped. When I first started loading for a belted magnum rifle and seen my brass dangerously stretched after 3 rounds I then learned to size off the shoulder rather than just trusting the belt. I take checking for possible case failure from stretching seriously. Only once did I scrap an entire lot. I bought 500 once fired cases from a guy on ebay and so many were dangerously stretched I decided to scrap the entire 500 cases. Takes some practice and a sharp wire to feel the stretch ring. If you think you feel a stretch ring cut the case apart and take a visual of what you're feeling then practice some with the cut-apart case. Definitely buy a case headspace gauge to set your dies to push the shoulder back a measured amount to fit your rifle or rifles. Hornady's Headspace Gauge set is my favorite and the RCBS Precision Mic is a fine tool. I like to measure rather than a drop in gauge. With a gauge that measures you can better check cases fired in your guns to see how much they expand forward.
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Home built 7.62x39 mauser on a large ring Turk K Kale mauser, which has small ring barrel, with Numerich small ring mauser 7.62x39 barrel. The chamber is cut tight to just a bit over min head space.
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Scooter22
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Another thought. Your having partial separation. . Is it possible part of the case head isn't being supported? Like at the bottom of the bolt/barrel junction where the rounds feed from the mag? I had a old 7x57 Spanish M93 with excessive head space that would start to show a partial ring at the on the case in that area consistently. Cases lasted 3 reloads.
The stretch ring is near middle of the brass, the chamber is fully supported. It is a mauser and the chamber is cut tight. The ring inside is about 80% -90% around and the line outside is about 3/4 around. The groove is very visible when cut open and the outside line catch finger nail once I find the line. Looking at the edge of the cut brass, the groove is not really that deep! I would say probably 1/4 of the brass thickness.
243winxb
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Nothing like a head separation. Keep shooting that brass.
Scooter22
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No it's not but he has something causing that ring. Might not be dangerous but it sholdn't be there. I'd still watch the brass and check the chamber to see if the reamer you used left a ridge. Good luck.
lindy
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Case separation is caused by to much head space. Or, You are sizing the case to short. Check the chamber with a headspce gage and then reset the barrel back to correct headspace. Throw those defective cases away before You get hurt !
Good shooting
Lindy
Good shooting
Lindy
jmorris
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Another vote for cutting the case open and seeing what it is you are feeling.
I made an attachment for a gauge I built that allows me to measure wall thickness without cutting the case in half.
If the brass is bad, don’t shoot it. If the brass is ok, then reload it. FWIW head separation generally isn’t a problem with the brass as much as a problem with how you are reloading them.
I made an attachment for a gauge I built that allows me to measure wall thickness without cutting the case in half.
If the brass is bad, don’t shoot it. If the brass is ok, then reload it. FWIW head separation generally isn’t a problem with the brass as much as a problem with how you are reloading them.
One piece doesn't necessarily condemn a whole batch. Bad pieces happen. Check to make sure you are not over sizing/pushing the shoulder back farther than needed.
Good advise.
It is from excess headspace, not lack of support for the case head. Size the brass to fit the chamber and eliminate the excess head clearance caused my excess mechanical headspace.
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