Notes on "Pierced" Primers
- Thread starter denton
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Before I knew what Winchester had done to the brass finish WSR I purchased a couple of sheaves. I think they were $65 to $70 for 5000!. That was prior to 1999, how times have changed. Anyway those brass finish WSR pierced with loads that never bothered the nickle finish WSR. So I called Winchester, talked to a character in the service department. He told me Winchester changed their primer, making it more sensitive, to "combat off center firing pin strikes". He was not happy when I told him that was stupid as it would increase the number of slamfires shooters would have in AR15's. Authority does not want to hear the down sides of their decisions. Anyway, what is obvious is that Winchester made the cups of brass finish WSR's thinner as the things ate up a handfull of AR15 firing pin tips.
I had to keep cutting and cutting loads, I think I was down 1.5 to 2 grains less, before the primers stopped piercing. And that is what you have to do if you want to use the thinner cupped commercial primers. It is not worth the cost of replacing firing pins, and I stopped using brass finish WSR.
However, CCI#34's have thicker cups and are appropriate for semi auto AR15's. They are part of CCI's mil spec product line, the things are less sensitive than commercial primers by virtue of having thicker cups, a greater anvil gap, and they are a "magnum" primer. Primarily so the round goes bang in arctic weather.
I had to keep cutting and cutting loads, I think I was down 1.5 to 2 grains less, before the primers stopped piercing. And that is what you have to do if you want to use the thinner cupped commercial primers. It is not worth the cost of replacing firing pins, and I stopped using brass finish WSR.
However, CCI#34's have thicker cups and are appropriate for semi auto AR15's. They are part of CCI's mil spec product line, the things are less sensitive than commercial primers by virtue of having thicker cups, a greater anvil gap, and they are a "magnum" primer. Primarily so the round goes bang in arctic weather.
JFrank
Member
Was not the original design a Large Primer ?
Dale Alan
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You are correct .
From the web.
CCI 7.62mm NATO-Spec Military Primers are a military large rifle primer containing magnum priming mix. The CCI #34 primers are a great choice for reloaders that use military cartridges. These primers are specially made to be harder to ignite which prevents slam fires in military type rifles with a floating firing pin. All CCI primers are continuously tested and improved. As a result today's CCI primers are more sensitive, easier to seat and more compatible with progressive and automated loading equipment than ever before. They utilize modern non-corrosive and non-mercuric initiator mixes for the cleanest burn possible.
JFrank
Member
So as a synopsis' we are changing the design then question the poor performance, is that about right?
NMexJim
Member
Interesting. I original choose CCI for my AR because they’re supposedly harder than WSR and the like, and less prone to slam fires. A quick look shows quite a few piercing complaints against 400. WSR actually seems to be preferred.
That said, I’ve put a whole bunch of 400 through my 5.56 w/o any leakage or other problems. I’m using LC brass, 400 primers, CFE223, 62gr FMJ right snug against max. My Irish luck. No pits in my bolt carrier yet.
Dale Alan
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I have shot thousands and thousands of 400s in ARs and bolts, never had a problem either ...and I don't the luck of the Irish, more like Polish and cursed .
243winxb
Member
No Joke. There is a difference in primers from lot to lot. CCI 400 primers may not be all the same. This is why each lot is tested.
My last lot of CCI 400 primers started to flow around the firing pin at mid-range loads. All with different weight bullets & 4 powder. As a test, I switched primers to Rem 7 1/2 . No more primer flow.
The 5.56/223 load data pressures are wide, as are the types of chambers.
Old, but still a good read- https://www.accurateshooter.com/cartridge-guides/223rem/
Google "DROP BALL TESTER for percussion primers"
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