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Reloading Berger Bullets


Flattened Primers?

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Unread 03-26-2010, 01:02 PM
Bronze Member
Join Date: Jan 2010
Location: West Virginia
Posts: 38
Flattened Primers?

Hi Folks,
I'm really not certain what a flattend primer (that i should be worried about) looks like.
After i shoot any bullet from min to max out of my 7mmRM, the primer never looks exactly like a brand new primer. It is always flatter.

I do not see any cratering from the firing pin but the primers are certainly flatter.

How do i know if i have a problem?
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Unread 03-26-2010, 03:25 PM
Silver Member
Join Date: Apr 2007
Location: Fort Morgan, Colorado
Posts: 408
Re: Flattened Primers?

Reading primers isn't totally reliable for determining chamber pressure but it certainly is a decent indicator. In my limited experience when the entire visible surface of the primer is flattened and the edge of the primer is almost indistinguishable you are in very excessive pressure. Usually when the primers are showing this deformation the case heads are also showing shiney spots, and often bolt lift is stiff when extracting the empty case.
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Unread 03-26-2010, 03:34 PM
Silver Member
Join Date: Jul 2008
Posts: 279
Re: Flattened Primers?

I am interested in seeing the responses to this topic. I question how good of an indicator they really are. I shoot an 06 and have had several factory loads with completely flattened primers.(Hornady and Winchester) Keep in mind that factory 06 ammo is designed to operate below 60,000 psi. Considering the same primers are used in a 270 which operates at 65,000 psi I have my doubts about flattened primers as a "tell all" pressure sign.
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Unread 03-26-2010, 03:41 PM
mkg mkg is offline
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Join Date: Nov 2007
Location: Satillite Beach, Florida
Posts: 178
Re: Flattened Primers?


Here are some pictures from another thread .
Keep in mind that some primers are "softer" than others and will show pressure signs quicker.

In my experiance federal are softer than CCI and CCI are softer than Winchester.

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Unread 03-26-2010, 04:11 PM
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Join Date: Nov 2008
Location: Lincoln, NE
Posts: 185
Re: Flattened Primers?

For me, the Win primers were softer than CCIs BR primers...load that flattened WLR primers didn't flatten the BR2s...

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