Is it normal for primers to become flattened, that is the radius that was on the outside edge to be completely gone? Since I am new to reloading this is the first time I have ever realy paid any attention to primers and their condition after firing. Or is it just a sign of normal pressure and happens quite often?

Thanks Dan

That's probably the only sign primers can give you of too hot a load. You best back off some, maybe a couple of grains. You're too hot I'd say.

Bob may well be right or you may have a bit of a headspace problem. Take some of the brass involved and reload them after NECK SIZING ONLY. If you still have a totally flattened primer do as Bob sea.

Dan,

There are a lot of things that could cause this and yes high pressure is one of them. There really needs to be more information we need before I would say that this is a high pressure sign.

-Is the bolt lift sticky?

-Are you using virgin brass?

-Are you using brass that has been over sized?

If you have a sticky bolt lift along with the flattened primers, then I would say you are far to high in pressure.

If you are using virgin brass, sometimes this will cause this problem, as will brass that has been over sized.

Let me explain what happens to cause this problem. When the firing pin impacts the primer, it drives the case forward into the chamber until either the shoulder stops in the chamber or the bullet stops on the rifling.

When the primer ignites the powder, the initial pressure expands the case to fill the forward portion of the chamber. Also the pressure pushes the primer back until it is stopped by the bolt face.

As pressure reaches max, the case head is slammed back against the bolt face which basically reseats the primer.

If the head space is to extreme and the primer is pushed back more then usual, it will create a flattened appearence, nomatter the pressure.

With a case that fits tight in a chamber, this will not and can not happen, making it easier to read a primer for pressure.

As I said before, you should look for alot of signs to determine pressure, the most useful being velocity measured over a chronograph as velocity is a direct result of pressure.

Good Shooting!!!

50

Fiftydriver is right. There are a lot of things that can make your primers look like those you describe. When I get these kinds of results, I DON'T AUTOMATICALLY ASSSUME MY LOAD IS TOO HOT!! BUT, when this happens, it is a clue to start an investigation, taking into account those things Fiftydriver listed. Pay close attention to sticky bolt lift, ejector/bolt face "smear" on case heads, primer fit when you reprime, and case life for repeated reloadings. IF YOU HAVE STICKY BOLT LIFT, THERE IS A MARKING FROM THE BOLT FACE OR EJECTOR ON THE CASE HEAD, OR YOUR NEW PRIMERS ARE A LOOSE FIT, you need to drop your powder charge by 5% or more.

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Larry

Thanks everyone, bolt lift does not seem to sticky,and there isn't any smears or marks on the case. I found a picture in the Nosler manual of 4 fired cases, two with blown or cratered primers and two that were normal. Mine kind of resemble the flattened one on the right that supposidly is ok. I just got a new chrony , haven't had a chace to use it yet, but I'll hve to check volocity on some of these .