Primer cup burn through

Discussion in 'Reloading' started by tfosters01, Mar 5, 2011.

  1. tfosters01

    tfosters01 Active Member

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    I have been using Remington large rifle 9 1/2 primers for my .308 load. I am loading 42.9 grains of 8208 with a 168 gr HPBT and getting 2507 fps muzzel velocity. It doesn't seem to be a "hot" load and well within reccomendation but the primer cups are burning pin holes through about 20% of the rounds right at the inside corner of the cup. Bad lot? Any advise would be greatly appriciated.
     
  2. BigSkyGP

    BigSkyGP Well-Known Member

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    It's been happening to me, too on my Small rifle primers, Remington's, CCI BR 4, and CCI 400's as well.

    It's not good, it will pit the face of your bolt, and or firing pin. Then they have to be repaired/and or replaced. Bad, worn or sharp firing pins can cause this. My firing pins are all new, and mirror smooth/round.
     

  3. boomtube

    boomtube Well-Known Member

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    "Bad lot?"

    Yep, it happens from time to time. Seems to be due to a too thin roll of brass the makers sometimes buy for making the primer cups. The tiny burn holes in the bolt face are unsighly but I've never known of it making a bolt unsafe or needing to be replaced.

    I don't see how a bad firing pin can make any primer cup burn through at the outside edge of it's shoulder.
     
    Last edited: Mar 6, 2011
  4. tfosters01

    tfosters01 Active Member

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    I'm thinking thin brass used for the cups because it is happening with my .308 and 22-250. Both are new rifles and I just bought a new bolt face for the Savage 22-250 because it is now pitted like you explained.
     
  5. BigSkyGP

    BigSkyGP Well-Known Member

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    Pitted bolts and firing pins is 30% of my business, as a small arms repairer for NG.

    One pit on a firing pin= unsevicable rifle.

    A pit or a few okay on the bolt. When you get a cluster of pits, wich becomes erosion=unservicable rifle.

    Needs to be able to survive a years duty in combat.
     
  6. boomtube

    boomtube Well-Known Member

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    "...the primer cups are burning pin holes through about 20% of the rounds right at the inside corner of the cup."

    Certainly burnt firing pins from a pierced or blanked primer need replacing but that doesn't seem to be the problem in this instance. And the "combat life" of a .308 sporting rifle is probably pretty good even if the bolt face has a few tiny craters around the primer circle! ;)
     
    Last edited: Mar 7, 2011
  7. BigSkyGP

    BigSkyGP Well-Known Member

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    Still sounds like poor primer manufacturing, whether it's in the f-pin dent, or around the cup's corner. As long as the peircing isn't from a bad/dammaged f-pin.
     
  8. fj40mojo

    fj40mojo Well-Known Member

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    Had the same problem with Rem small rifle BR in my .223. Known load that I've been shooting for years, only change was from CCI to the Rem BR primers. I've got 800 Rem BR primers for someone if they want them, garbage as far as I'm concerned.