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Irregular Primer Indentation

Computer Kid
Below is a link to a VERY high res image of some casings coming out of a S&W sw99 .40 cal. If you look at the primer indentations, they are not perfectly round. Has anyone seen this before and may have some insight about why this gun is doing this? It's brand new and only has about 90 rounds fired through it. All of the fired rounds seem to be having this issue. Is this normal or something I should be worrying about? I don't want extra wear on the pin as to shorten the lifetime of the firearm.

My theory is that the firing pin is not completely retracted while the casing is ejected, and the casing is being pushed back onto the pin at an angle and causing the extra oblong indentation.

I just checked the fired casing that came with the firearm when it was purchased. It ALSO has the same problem. So we know it came from the factory this way.

This is a pretty big picture file, so be warned. You may have to scroll around a bit to see all the casings.

Thanks for any insight.

http://tj.hunterhome.org/images/primer.jpg
"They that can give up essential liberty to obtain a little temporary saftey deserve neither liberty nor saftey." -- Benjamin Franklin, 1759
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Comments

5 comments

Date Votes
  • perry shooter
    How large is the tip of the firing pin in relation to the size of the hole in the breach face of slide?
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  • ATF
    Seen it happen many times to a bunch of different guns.To me this is normal ,the round has started to eject this is how this happens.
    [:)]

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    A little lemon and seltzer will remove those pesky ink stains after you've been fingerprinted. "
    Martha Stewart







    ATF,Eagle Guns
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  • Computer Kid
    Well, it looks like it's just the right size to fit through without any wiggle room on either side. I'll see if I can post some pictures here in a little while.
    "They that can give up essential liberty to obtain a little temporary saftey deserve neither liberty nor saftey." -- Benjamin Franklin, 1759
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  • Iconoclast
    CK - first off, welcome to the forums!

    I think ATF nailed it. I could show you the same thing on my own brass (fired from a Glock), 1xF brass I've purchased for reloading and range pickups (in one case I know the firearm used was a SIG). Most of it .40 S&W caliber - so it's likely an intrinsic manifestation of that round's internal ballistics. I honestly don't think you have anything to be concerned about with this. If the primers were pierced, flattened, cratered, etc., it might be a different story, but I see no such indications of potential problems in these photos.

    PS - really nice job on the photos; that sort of evidence is often lacking when a question is asked - and not just by those new to this place. Very helpful.

    "There is nothing lower than the human race - except the French." (Mark Twain) ". . . And DemoCraps" (me)
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  • Hangfire
    It happens quite often. I've always heard it referred to as primer wipe.As others have said, not a problem. A soft primer WILL NOT wear on your firing pin.

    Love them Pre-64's!!!!-Bob
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