Should I throw away brass with high pressure signs?

[W123driver]

Hello,

I've been reloading 7x57 Mauser with mild-to moderate loads for target shooting, and decided to put some hot loads for upcoming gun season. I think I have what others describe as high pressure signs: Flattened primers and slight elongation of shell head (the brass is shiny in that area and i can feel slight groove there with a finger. There are no cracks. My question is if I can reuse this brass safely and if accuracy will suffer. I would not care if it was commonly available brass, but this stuff was pricey... (Norma). Thank you

[SteveWag]

You can use brass that has been fired with a very heavy load. First neck size only, segregate cases and use them only in the chamber they came from. Full length sizing will result in head separation. Second, feel how the primers seat. Use a hand primer or a bench primer, do not use a press to prime. If you can feel a small pressure when seating, things are OK. If you are seeing cases growing in length (need trimming) you are resizing incorrectly.
Steve

[Cyo]

I tend to be very cautious with regards to using brass. If it's relatively new brass--1 or two reloads--I'll continue to use it and keep a close eye on it. If I've reloaded it a few times and I'm seeing high pressure signs beyond a flattened primer, I toss it.

I also only neck size ever since I only have reloaded for the same rifles all the time.

[andrewjs18]

Hello,

I've been reloading 7x57 Mauser with mild-to moderate loads for target shooting, and decided to put some hot loads for upcoming gun season. I think I have what others describe as high pressure signs: Flattened primers and slight elongation of shell head (the brass is shiny in that area and i can feel slight groove there with a finger. There are no cracks. My question is if I can reuse this brass safely and if accuracy will suffer. I would not care if it was commonly available brass, but this stuff was pricey... (Norma). Thank you

I wouldn't throw it away....If you don't feel it's safe to shoot, put it in a 2 liter soda can or something and take it to the scrap yard when you get enough..you at least might be able to get a few bucks for it so then you can buy more powder or primers or whatever...

[Pete D.]

Take one of the cases and cut it length-wise. If you can see an indented ring in the case near where you felt it with your probe, don't use them. Firing cases with incipient case head separations is taking more risk than I'd be willing to. The case has been compromised; sell them for scrap or toss them.
Pete

[mardo]

Take one of the cases and cut it length-wise. If you can see an indented ring in the case near where you felt it with your probe, don't use them. Firing cases with incipient case head separations is taking more risk than I'd be willing to. The case has been compromised; sell them for scrap or toss them.
Pete

Agreed.Stretched cases are not something that you want to mess with. Work up slower with you next loads.

[grvj]

SteveWag

...I have 7x57 cases, a few that separated at the base, and noted the comment of full-sizing a possible cause.

I am assuming this is because the case is being overworked though I have full-sized 30.06 brass multiple times with no cracked necks, head separations or other failures.

Could you offer details of the sizing particulars that can cause head seoparation?

[Pete D.]

Most frequently (always?), case head separation is caused by excess headspace. That condition is most frequently caused by improperly adjusted sizing dies, though it can also be a function of the firearm itself. Have you had the firearm checked with a headspace (go/no go) gauge?
Pete

[SteveWag]

When bottlenecked brass is fired in a given chamber, the fired brass has expanded to fit the chamber. Typical brass springs back about 0.005-inches, but the fired brass fits THAT chamber almost perfectly.

If the unfired cartridge was held froward in the chamber, as is mostly the case, then the firing pin holds it forward as the powder begins to burn and increase internal pressure. As the internal pressure increases, the case walls expand and grip the chamber walls tightly. THEN the case head is pushed rearward until it contacts the bolt face. THRE is the rub, with the case walls being held tight, all rearward expansion all takes place just ahead of the solid part of the case head. This is because the solid head is not expanded, or gripping the chamber walls.




The amount of expansion is a function of the amount of “looseness”, lengthwise, of the case in the chamber. Once fired, this “looseness” is almost none, IF, the length of the case is not changed during sizing. BUT, if you follow the instructions in most reloading manuals, you would set the full-length die to restore the manufacturers length. THIS IS BAD! If you can segregate brass by firearm, AND, not decrease the length during firing, 23 to 30 reloads are typical. Without length-wise expansion, the neck will split before anything else fails.

Repeated sizing and changing the length (shortening) will cause the accumulated stretching (all in one place) to result in case head separation

Steve.