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Thread: Cratered Primers

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    Member moses42ak's Avatar
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    Default Cratered Primers

    Out at the range today working on handloads for a new 300 WM (New model 70). All of my primers are cratered, from starting loads to a half grain below max as per the Speer manual. I blew 2 primers during all the fun. In speaking with a fellow out there he asked if I had the same problem with factory ammo to which I replied that I had never fired factory stuff in this particular rifle. He throws me a couple rounds that I fire and lo and behold....cratered primers. Any ideas as to what the problem may be?

  2. #2

    Default One possibility

    Check to see if the firing pin hole in the bolt face looks oversized. I thought of excess headspace too as a secondary thought. I'd take it to a reliable gunsmith.

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    New Model 70? warranty issue. Bring it by

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    Yes, new model 70. I'll take it back to where I bought it. Thanks

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    Default

    When I first started loading my commercial M98 I noticed cratered primers and some pierced primers. I had not looked closely at any of my factory fired rounds though none had pierced. Later I noticed some cratering with factory rounds. I pulled the firing pin and found it was not very smooth, after some work on a knife shapening stone to give it a nice round tip I have never had another pierced primer. There is still a little cratering but the firing pin is rather loose in the hole so I have concluded that is a gun issue. As others have said check the fit of firing pin and the shape of the tip. If an new rifle it maybe better to send it back to the factory, at the cost of the new Winchesters they really should not have these problems.

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    Default

    Quote Originally Posted by moses42ak View Post
    Out at the range today working on handloads for a new 300 WM (New model 70). All of my primers are cratered, from starting loads to a half grain below max as per the Speer manual. I blew 2 primers during all the fun. In speaking with a fellow out there he asked if I had the same problem with factory ammo to which I replied that I had never fired factory stuff in this particular rifle. He throws me a couple rounds that I fire and lo and behold....cratered primers. Any ideas as to what the problem may be?
    Regarding the primers that were "blown"...were the primers pierced by the firing pin, or were they completely blown out of the primer pocket without being pierced? If they were flattened and blown out of the pocket intact, it's more than a firing pin issue.

    Doc

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    Member moses42ak's Avatar
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    Default

    By blown, I mean pierced. There's a nice little black hole where the firing pin struck the primer.

  8. #8

    Default Well, then

    chances are the firing pin is too long or has a rough tip as was mentioned. Should be an easy fix. Are you sure your primers were seated all the way to the bottom of the primer pocket? Some folks still seat primers flush with the rear end of the case instead of pressing them in until the bottom of the pocket is contacted.
    Last edited by mauserboy; 09-27-2009 at 16:10. Reason: correct spelling

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    Quote Originally Posted by mauserboy View Post
    chances are the firing pin is too long or has a rough tip as was mentioned. Should be an easy fix. Are you sure your primers were seated all the way to the bottom of the primer pocket? Some folks still seat primers flush with the rear end of the case instead of pressing them in until the bottom of the pocket is contacted.
    Agreed, they need to be seated a little bit into the bottom.
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    Quote Originally Posted by moses42ak View Post
    By blown, I mean pierced. There's a nice little black hole where the firing pin struck the primer.
    I think it's either a headspace or firing pin problem, and I'll bet it's the firing pin. Your decision to return it for waranty work sounds like a good idea Moses42AK.. Provide them with a detailed description of the problem as you have done in this thread, especially noting that it also happened with factory loads. Thanks for sharing your experience with us, and good shooting to you down the road.

    Nice reminder MB and NM about seating primers to the base of the pocket.

    Doc

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    Member moses42ak's Avatar
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    Had it not happened with factory ammo, I would have reconsidered my handloads (which I seat below flush) but since it was consistent even with factory ammo I figured there was more to it.

    I'm going to take it in tomorrow and see what happens.

    Thanks to all.

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    Finally getting over the swine flu and ran it in today. A quick check of another bolt from a different 300 shows nothing seemingly wrong with the firing pin. They threw together a quick go-no-go headspace guage and it looks good in mine and another new Model 70 but put it in a Remington and it's not happening. Left it at the shop and they called the Winchester people. Won't hear anything until probably Monday.

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    Quote Originally Posted by moses42ak View Post
    300 WM (New model 70). All of my primers are cratered, ...... I blew 2 primers during all the fun.
    Do you mean blew them out of the cases or just pierced a hole in them and left a black hole where the gase leaked out?
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    Hey Murphy, I stated earlier that by blown I mean pierced. Nice little black holes.

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