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yamoon
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Primer cup strength
Nov 6th, 2015 at 10:11pm
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Is the primer cup material on large rifle mag primers thicker and stronger than standard rifle primers? After reading the fine article by Byron Goff, I decided to blow the dust off of a Kettner action chambered in 6mm Krag long. Every 3rd or 4th round the primer ruptures in the on the edge. The problem is the 2 holes used by the spanner to remove the fireing pin retainer extend slightly under the primer, not a problem with the modest 8.15x46R is a problem with the higher pressure 6mm Krag. Any help appreciated. Thanks Mike
  
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yamoon
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Re: Primer cup strength
Reply #1 - Nov 6th, 2015 at 10:13pm
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I am currently using Federal large rifle bench rest primers.
Mike
  
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Cat_Whisperer
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Re: Primer cup strength
Reply #2 - Nov 6th, 2015 at 10:34pm
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I would think not.  BUT, a pair of calipers would tell you immediately.  Might could be a good question to pose directly to the manufacturers.

Thickness is one consideration in the strength of the material.  Material composition and hardness (brittleness) is another - also influenced by the shape and depth of penetration of the firing pin.

Another consideration is the sharp increase in pressure (a little increase in velocity) when the primer hole is enlarged.  (See Phil Sharpe's volume)
  

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EricJ
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Re: Primer cup strength
Reply #3 - Nov 7th, 2015 at 12:32am
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Yes primers have a different thickness and make of the cup.  German Salazar did an awesome article on primers and posted it in 2009 in his blog, but it seems now that he has locked it down.  James Calhoon did a small test as well, but it doesn't have near the info that German's had.  (You need to Login or Register to view media files and links)

You might be able to contact German on the 6mmbr website and have him send you a copy or a working link to his experiment.
  
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.22-5-40
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Re: Primer cup strength
Reply #4 - Nov 7th, 2015 at 1:27am
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Rather than risk erosion of action face from blown primers..why not just reduce loads?
  
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yamoon
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Re: Primer cup strength
Reply #5 - Nov 7th, 2015 at 4:01pm
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The loads are moderate show no signs of pressure. 30gr IMR3031 behind a 90gr Speer BTSP. Cronograph at 2750 fast.
Mike
  
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