Check out this primer crater??

Discussion in 'Small Stuff--22s, 20s, and 17s' started by vmaxpro, Mar 17, 2011.

  1. vmaxpro

    vmaxpro Site $$ Contributor

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    223 40gr vmax in front of 29gr h335 rem 7.5, lapua brass. Its hard to see but it looks like the crater raised waaay up almost to a piercing. Ive measured the brass and everything looks great? The primers not even flattened. Heres the thing, the firing pin measures .080 and its hole is a nice fit, but it protrudes .066! Should I have this shortend to .045 and turned/bushed to .062?
     

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  2. RJinTexas

    RJinTexas Site $$ Contributor

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    Are you absolutely sure you do not have excessive head space, I've never seen a primer back out that far when the head space was correct. Did also pierce the primer?

    RJ
     
  3. NorCalMikie

    NorCalMikie Site $$ Contributor

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    Like RJ mentioned, headspace? Case too short for the chamber and primer backed out when fired before being forced back against firing pin? Was the brass fireformed to that chamber?
     
  4. ab_bentley

    ab_bentley

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    Maybe a sloppy firing pin is the culprit. Adam
     
  5. HillbillySniper

    HillbillySniper Send It!

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    I agree with all the gents. My only thing is my 223AI has always done that. Now I do shot a slight compressed load but that's the norm for my rifle I have fire formed all my brass a couple times and only trimmed after the first firing but only enough to uniform all my brass.


    Hillbilly
     
  6. Joe O

    Joe O

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    I agree with the fellows above.Looks like two problems,the least of which is the cratering.The headspace needs to be checked,as the primer does not show high pressure,just a misfit fireing pin.
     
  7. 1shot

    1shot

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    I also agree it’s a head space issue. On the off chance that it isn’t, check your firing pin spring for strength or damage.
    I hope this helps,
    Lloyd
     
  8. vmaxpro

    vmaxpro Site $$ Contributor

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    I think the headspace might be ok? The primer didnt actually back out its just the " crater" that flowed that far back. Theres no slop in the pin either. Do you guys think the firing pin is too big and the spring is weak? Its a Howa 1500. Thanks for all the replies!
     
  9. NorCalMikie

    NorCalMikie Site $$ Contributor

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    Was the brass fireformed to the chamber? If not, when it got fired it pushed the primer out "some" before it got pushed back against the bolt head. I bet if you tried to reseat the primer it would go back in a bit?? JMHO.
     
  10. mikecr

    mikecr

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    Were the flash holes opend up?
    And .045 protrusion does sound better to me. I recently tuned this with a 223 Cooper bolt, finding that greater than .045(by coincidence) opened my groups. So I backed it off until finding a perfect sweetspot for Feds. Would have to check my log to find the exact value.
     
  11. vmaxpro

    vmaxpro Site $$ Contributor

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    2nd firing on the brass. Upd the charge .5gr. Primer still seated tight so im lost haha. How can i test the spring? Even on a very mild charge I get some flow.
     
  12. SpencerC

    SpencerC

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    I would reset your protrusion at .045 and see what it looks like. It's 50%longer than ideal at the moment and it will make somewhat of a difference.
     
  13. skeetlee

    skeetlee Lee Gardner Precision Site $$ Contributor

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    Bottom line is that isnt good. It isnt safe, and it isnt supposed to happen. You have an issue that needs addressed asap. Probably excessive headspace. Get it fixed!! Lee
     
  14. vmaxpro

    vmaxpro Site $$ Contributor

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    Wouldnt the datum line stretch w/ excessive headspace tho? I mean by measuring a fired vs sized case.
     
  15. 6BRinNZ

    6BRinNZ

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    I have a Howa 1500 Supreme varminter in .223 and 6mmBR. Both of these have the factory bolt face and firing pin. I use ADI powders and with hot loads on an unbushed bolt face and using a hard primer such as CCI 400s and 450s I have seen the primer flow as in your first picture...its basically a nipple, and its so large you probably couldn't fit it into a shell holder to resize the case. Softer primers would have pierced.

    For me I have found that primer piercing or excessive primer flow will be the first pressure signs in an unbushed bolt face, typically it appears in the vicinity of max to .5 grn over the max load, I don't normally have primer pocket or case expansion issues on an unbushed bolt face so I don't use them to judge the load. In a bushed bolt face its a totally different story.

    But I haven't seen anything like what you have in the second picture. The diameter of the primer flow typically looks the size of the firing pin from what I have experienced, it looks nothing like that picture. As the guys have mentioned I would typically see a little more primer flattening than what is in your picture.

    How hot are your loads? Based on the second picture I would get things checked out, and or check the load for something that would cause high pressures. I also agree with the guys about the excessive head space as I understand it can cause pressure like symptoms among other things.

    Be careful and good luck!
     
  16. vmaxpro

    vmaxpro Site $$ Contributor

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    Ok, just checked the headspacing with a friends gage set and everything seems ok in that department. The load is def on the heavy side @29.5gr h335, 40gr vmax 2.228 col, 7.5, lapua brass. Im def NOT going to use this load and I think I'll back off to 28.5 to be safe. I just thought it was strange for the primer to flow that bad with no other signs ???
     
  17. RJinTexas

    RJinTexas Site $$ Contributor

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    If your absolutely certain that you don't have a head space issue. Call Gre-Tan Rifles and have Greg bush your firing pin hole and turn the firing pin for a precise fit. I got tired of having an occasional pierced primer on my hot little 17 Mach IV an one of my 22BR's so I gathered up every 700, XP and Savage bolt that I owned an shipped them to Greg. I haven't even seen any cratering much less a pierced a primer since shooting the exact same loads. His turn around time is usually under 10 days.

    RJ
     
  18. 6BRinNZ

    6BRinNZ

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    To be honest I think this is explained by a combination of good components etc in an unbushed boltface setup (I would still get a smith to check it out though..that second pic looks odd). I think Laupua brass is so good (no sticky bolt lift) and the hard primers are thick enough to allow a lot of flow before piercing, that in an unbushed boltface you will get this happening. Certainly it has been my experience anyways. As mentioned once the boltface is bushed its a whole different story.....

    Also I cantacted Gre-tan a while back and he confirmed that he did Howa Bolts...I never ended up going through with it though.
     
  19. DanCarey

    DanCarey Site $$ Contributor

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    In the old days when most bench rifles were made using Remington actions, no one bushed the bolts, then again, gunsmiths wives didn't drive BMW's either.
     
  20. jonbearman

    jonbearman I live in new york state,how unfortunate ! Site $$ Contributor

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    How do you set the protusion of a firing pin in lets say a remington?
     

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