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Thread: primer cratering

  1. #1

    primer cratering

    BRNO Fox Md 2 .222
    20" barrel
    60gr SP - 21gr N133
    50gr Vmax - 22.1gr N133
    Norma Brass (neck sized)
    CCI 400 Small rifle primers

    OAL 55.55mm (SP tip)






    havent looked at the firing pin hole yet but am hoping it has an oversized hole.
    strike is not too deep and there are no symptoms of high pressure

    other than the cosmetic appearance is there any real reason to be concerned?
    Last edited by bewsher500; 04-02-2013 at 10:52.

  2. #2
    May be that the primer is a little too soft. Try a bench rest primer and I expect the issue will resolve. I have similar problems if i load heavy bullets in my .223, standard CCI crater, but Remmy 7.5's are fine.

    D

  3. #3
    hi feller
    penny worth
    A few possibilities.

    1. The cartridges are loaded too hot.
    2. Firing pin depth is too shallow.
    3. Weak firing pin spring.
    4. Excessive headspace.

    #4 is easy to check with a set of headspace gauges and is a common problem with milsurps.

    Best way to check #1 is to fire a few rounds from the same lot in a different rifle and see if a similar cratering effect occurs.

    may help i get this when runner hot loads for 1,000 ydr target work in .308 with 190 vld's

    PS edit try use'g mag rifle small primes not just small rifle ! one of your pals may have some to try.

    Quote Originally Posted by bewsher500 View Post
    BRNO Fox Md 2 .222
    20" barrel
    60gr SP - 21gr N133
    50gr Vmax - 22.1gr N133
    Norma Brass (neck sized)
    CCI 400 Small rifle primers

    OAL 55.55mm (SP tip)






    havent looked at the firing pin hole yet but am hoping it has an oversized hole.
    strike is not too deep and there are no symptoms of high pressure

    other than the cosmetic appearance is there any real reason to be concerned?
    Last edited by paul o'; 04-02-2013 at 12:12.

  4. #4
    Quote Originally Posted by paul o' View Post
    hi feller
    penny worth
    A few possibilities.

    1. The cartridges are loaded too hot.
    2. Firing pin depth is too shallow.
    3. Weak firing pin spring.
    4. Excessive headspace.

    #4 is easy to check with a set of headspace gauges and is a common problem with milsurps.

    Best way to check #1 is to fire a few rounds from the same lot in a different rifle and see if a similar cratering effect occurs.

    may help i get this when runner hot loads for 1,000 ydr target work in .308 with 190 vld's

    PS edit try use'g mag rifle small primes not just small rifle ! one of your pals may have some to try.

    Unfortunately this is actually a case of firing pin clearance.

  5. #5
    hmm primmer flow passed fireing worn pin hole in bolt head fault pos'? but has this been the case on all inc factory loads he has fired, without seeing rifle its a gess by all me thinks, so many reasions why the case's may look this way .why not have his rifle sent down to you so you can say without any other factors this is the case mty as per #3

  6. #6
    I have this with a rem 700 .30mag, it was a bit worrying until i talked to remmington and did searches on the net and it turns out they have a factory designed recessed firing pin hole and its supposed to do it !

  7. #7
    Quote Originally Posted by paul o' View Post
    hmm primmer flow passed fireing worn pin hole in bolt head fault pos'? but has this been the case on all inc factory loads he has fired, without seeing rifle its a gess by all me thinks, so many reasions why the case's may look this way .why not have his rifle sent down to you so you can say without any other factors this is the case mty as per #3
    Not necessarily worn but definitely pin clearance.

    Your selection of 'problems' gives away your inexperience, none of your 'guesses' tally with the photo!

  8. #8
    Quote Originally Posted by Double four View Post
    I have this with a rem 700 .30mag, it was a bit worrying until i talked to remmington and did searches on the net and it turns out they have a factory designed recessed firing pin hole and its supposed to do it !
    Yup your are correct D4
    QUOTE:-
    [from remington 700 armorer's course sheet
    2004 and newer 700's.
    In the last few years Remington has been designing there 700's to crater primers on purpose. They've added a very very slight bevel to the firing pin hole so that primer cratering occurs during case expansion. This causes the primer metal to drift forward and thicken at the lip of the cratering and the dome of the firing pin strike. Remington said they even have primer cutaways back at the factory that proves it works.
    Normally, cratering comes around from having too much pressure in a hand load and when the case contracts, it hits the bolt face hard enough to bounce the firing pin back and material flows into the firing pin hole.] end qoute

  9. #9
    Quote Originally Posted by j0e_bl0ggs View Post
    Not necessarily worn but definitely pin clearance.

    Your selection of 'problems' gives away your inexperience, none of your 'guesses' tally with the photo!
    hmm gess reminton arms are wrong then iam "ex practical pistol maker" so i must be wrong aswell mty as said without seeing rifle ?????? its glass ball time , got any numbers for this week

  10. #10
    nothing like a good forum punch up...you go chaps, up and at em'

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